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Alabama

Section 30-1-3
Issue of incestuous marriages not deemed illegitimate.
The issue of any incestuous marriage, before the same is annulled, shall not be deemed illegitimate.

Section 13A-13-3
Incest.
(a) A person commits incest if he marries or engages in sexual intercourse with a person he knows to be, either legitimately or illegitimately:
(1) His ancestor or descendant by blood or adoption; or
(2) His brother or sister of the whole or half-blood or by adoption; or
(3) His stepchild or stepparent, while the marriage creating the relationship exists; or
(4) His aunt, uncle, nephew or niece of the whole or half-blood.
(b) A person shall not be convicted of incest or of an attempt to commit incest upon the uncorroborated testimony of the person with whom the offense is alleged to have been committed.
(c) Incest is a Class C felony.
(Acts 1977, No. 607, p. 812, 7010.)

http://www.legislature.state.al.us/CodeofAlabama/1975/22063.htm

Alaska

AS 25.05.021. Prohibited Marriages.
Marriage is prohibited and void if performed when
(1) either party to the proposed marriage has a husband or wife living; or
(2) the parties to the proposed marriage are more closely related to each other than the fourth degree of consanguinity, whether of the whole or half blood, computed according to rules of the civil law.

Editors note: (first cousins are of the fourth degree thus Alaska does not prohibit 1st or more distant cousins from marrying)

http://www.touchngo.com/lglcntr/akstats/Statutes/Title25/Chapter05.htm

Arizona

25-101. Void and prohibited marriages
A. Marriage between parents and children, including grandparents and grandchildren of every degree, between brothers and sisters of the one-half as well as the whole blood, and between uncles and nieces, aunts and nephews and between first cousins, is prohibited and void.
B. Notwithstanding subsection A, first cousins may marry if both are sixty-five years of age or older or if one or both first cousins are under sixty-five years of age, upon approval of any superior court judge in the state if proof has been presented to the judge that one of the cousins is unable to reproduce.
C. Marriage between persons of the same sex is void and prohibited.

13-3608. Incest; classification
Persons who are eighteen or more years of age and are within the degrees of consanguinity within which marriages are declared by law to be incestuous and void, who knowingly intermarry with each other, or who knowingly commit fornication or adultery with each other are guilty of a class 4 felony.

http://www.azleg.state.az.us/FormatDocument.asp?inDoc=/ars/25/00101.htm&Title=25&DocType=ARS

Arkansas

9-11-106. Incestuous marriages - Penalties for entering into or solemnizing.

(a) All marriages between parents and children, including grandparents and grandchildren of every degree, between brothers and sisters of the half as well as the whole blood, and between uncles and nieces, and between aunts and nephews, and between first cousins are declared to be incestuous and absolutely void. This section shall extend to illegitimate children and relations.

(b) Whoever contracts marriage in fact, contrary to the prohibitions of subsection (a) of this section, and whoever knowingly solemnizes the marriage shall be deemed guilty of a misdemeanor and shall upon conviction be fined or imprisoned or both, at the discretion of the jury who shall pass on the case, or if the conviction shall be by confession, or on demurrer, then at the discretion of the court.

5-26-202. Incest.

(a) A person commits incest if, being sixteen (16) years of age or older, he purports to marry, has sexual intercourse with, or engages in deviate sexual activity with a person he knows to be:

(1) An ancestor or a descendant; or
(2) A stepchild or adopted child; or
(4) An uncle, aunt, nephew, or niece; or
(5) A stepgrandchild or adopted grandchild.
(b) The relationships referred to in this section shall include blood relationship without regard to legitimacy.
(c) Incest is a Class C felony; however, incest is a Class A felony if the victim is under sixteen (16) years of age and the perpetrator is over twenty-one (21) years of age at the time of the offense.

http://www.arkleg.state.ar.us/lpbin/lpext.dll/newSdCode/7dd1/7e54/7f8f?f=file[document.htm]#JD_8d93

California

FAMILY.CODE
SECTION 2200-2201

2200. Marriages between parents and children, ancestors and
descendants of every degree, and between brothers and sisters of the
half as well as the whole blood, and between uncles and nieces or
aunts and nephews, are incestuous, and void from the beginning,
whether the relationship is legitimate or illegitimate.

http://www.leginfo.ca.gov/cgi-bin/calawquery?codesection=fam&codebody=&hits=20

Colorado

14-10-111. Declaration of invalidity. (1) The district court shall enter its decree declaring the
invalidity of a marriage entered into under the following circumstances:
[...]

(I) A marriage entered into prior to the dissolution of an earlier marriage of one of the parties;
(II) A marriage between an ancestor and a descendant or between a brother and a sister, whether the relationship is by the half or the whole blood;
(III) A marriage between an uncle and a niece or between an aunt and a nephew, whether the relationship is by the half or the whole blood, except as to marriages permitted by the established customs of aboriginal cultures;

18-6-301. Incest. (1) Any person who knowingly marries, inflicts sexual penetration or sexual intrusion on, or subjects to sexual contact, as defined in section 18-3-401, an ancestor or descendant, including a natural child, child by adoption, or stepchild twenty-one years of age or older, a brother or sister of the whole or half blood, or an uncle, aunt, nephew, or niece of the whole blood commits incest, which is a class 4 felony. For the purpose of this section only, "descendant" includes a child by adoption and a stepchild, but only if the person is not legally married to the child by adoption or the stepchild.
(2) When a person is convicted, pleads nolo contendere, or receives a deferred sentence for a violation of the provisions of this section and the victim is a child who is ten years of age or older and under eighteen years of age and the court knows the person is a current or former employee of a school district in this state or holds a certificate or letter of authorization pursuant to the provisions of article 60 of title 22, C.R.S., the court shall report such fact to the department of education.

http://statute.intellinetusa.com/stat99/

Connecticut

Sec. 46b-21. (Formerly Sec. 46-1). Kindred who may not marry.

No man may marry his mother, grandmother, daughter, granddaughter, sister, aunt, niece, stepmother or stepdaughter, and no woman may marry her father, grandfather, son, grandson, brother, uncle, nephew, stepfather or stepson. Any marriage within these degrees is void.
(1949 Rev., S. 7301; P.A. 78-230, S. 3, 54.)
History: P.A. 78-230 changed wording slightly and substituted "may" for "shall"; Sec. 46-1 transferred to Sec. 46b-21 in 1979.
See Sec. 53a-191 re incest.
Annotations to former section 46-1: Does not prohibit marriage with deceased husband's brother. 12 C. 94. "Sister" includes half sister for purpose of incest prosecution. 132 C. 165. The marriage of a niece and her uncle in Italy, though valid there and contracted without intent to evade the law of this state, held not valid in this state. 148 C. 288. (One judge dissenting.) Relationship of niece-in-law and uncle-in-law held not within enumerated relationships for crime of incest. 158 C. 461. Annotations to present section: Former section General Statutes (Rev. 1949) S. 7301 cited. 182 C. 344, 347. Relationship as half-uncle and half-niece is void. 213 C. 637642, 644646, 649, 656.

http://www.cslnet.ctstateu.edu/statutes/index.htm

DC

30-101. Marriages void ab initio - In general.

The following marriages are prohibited in the District of Columbia and shall be absolutely void ab initio, without being so decreed, and their nullity may be shown in any collateral proceedings, namely:
(1) The marriage of a man with his grandmother, grandfather's wife, wife's grandmother, father's sister, mother's sister, mother, stepmother, wife's mother, daughter, wife's daughter, son's wife, sister, son's daughter, daughter's daughter, son's son's wife, daughter's son's wife, wife's son's daughter, wife's daughter's daughter, brother's daughter, sister's daughter;
(2) The marriage of a woman with her grandfather, grandmother's husband, husband's grandfather, father's brother, mother's brother, father, stepfather, husband's father, son, husband's son, daughter's husband, brother, son's son, daughter's son, son's daughter's husband, daughter's daughter's husband, husband's son's son, husband's daughter's son, brother's son, sister's son;

INCEST
Section 22-1901. Definition and penalty.

22-1901. Definition and penalty.
If any person in the District related to another person within and not including the fourth degree of consanguinity, computed according to the rules of the Roman or civil law, shall marry or cohabit with or have sexual intercourse with such other so-related person, knowing him or her to be within said degree of relationship, the person so offending shall be deemed guilty of incest, and, on conviction thereof, shall be punished by imprisonment for not more than 12 years.
http://www.lexislawpublishing.com/sdCGI-BIN/om_isapi.dll?clientID=2494&hitsperheading=on&infobase=dccode.NFO&record={130FB}&softpage=Document

Delaware

(a) A marriage is prohibited and void between a person and his or her ancestor, descendant, brother, sister, uncle, aunt, niece, nephew, first cousin or between persons of the same gender.

766. Incest; class A misdemeanor.
a) A person is guilty of incest if the person engages in sexual intercourse with another person with whom the person has one of the following relationships:
A male and his child.
A male and his parent.
A male and his brother.
A male and his sister.
A male and his grandchild.
A male and his niece or nephew.
A male and his father's sister or brother.
A male and his mother's sister or brother.
A male and his father's wife.
A male and his wife's child.
A male and the child of his wife's son or daughter.
A female and her parent.
A female and her child.
A female and her brother.
A female and her sister.
A female and her grandchild.
A female and her niece or nephew.
A female and her father's sister or brother.
A female and her mother's sister or brother.
A female and her mother's husband.
A female and her husband's child.
A female and the child of her husband's son or daughter.

(b) The relationships referred to herein include blood relationships without regard to legitimacy and relationships by adoption.
Incest is a class A misdemeanor and is an offense within the original jurisdiction of the Family Court.

Incest
(a) A person is guilty of incest when he marries a person whom he knows to be related to him within any
of the degrees of kindred specified in section 46b-21. (b) Incest is a class D felony.

http://www.lexislawpublishing.com/sdCGI-BIN/om_isapi.dll?clientID=2491&hitsperheading=on&infobase=decode.NFO&record={122A5}&softpage=Document

Florida

741.21 Incestuous marriages prohibited.--A man may not marry any woman to whom he is related by lineal consanguinity, nor his sister, nor his aunt, nor his niece. A woman may not marry any man to whom she is related by lineal consanguinity, nor her brother, nor her uncle, nor her nephew.

826.04 Incest.--Whoever knowingly marries or has sexual intercourse with a person to whom he or she is related by lineal consanguinity, or a brother, sister, uncle, aunt, nephew, or niece, commits incest, which constitutes a felony of the third degree, punishable as provided in [...] "Sexual intercourse" is the penetration of the female sex organ by the male sex organ, however slight; emission of semen is not required.

http://www.leg.state.fl.us/citizen/documents/statutes/StatuteBrowser99/index.cfm?Mode=Display_Statute&URL=Ch0741/titl0741.htm

Geogia

19-3-3 G *** CODE SECTION *** 10/15/99

(a) Any person who marries a person to whom he knows he is related,
either by blood or by marriage, as follows:

(1) Father and daughter or stepdaughter;
(2) Mother and son or stepson;
(3) Brother and sister of the whole blood or the half blood;
(4) Grandparent and grandchild;
(5) Aunt and nephew; or
(6) Uncle and niece

shall be punished by imprisonment for not less than one nor more
than three years.

(b) Marriages declared to be unlawful under subsection (a) of this
Code section shall be void from their inception.

16-6-22. (a) A person commits the offense of incest when he engages in sexual intercourse with a person to whom he knows he is related either by blood or by marriage as follows: (1) Father and daughter or stepdaughter; (2) Mother and son or stepson; (3) Brother and sister of the whole blood or of the half blood; (4) Grandparent and grandchild; (5) Aunt and nephew; or (6) Uncle and niece. (b) A person convicted of the offense of incest shall be punished by imprisonment for not less than one nor more than 20 years.

http://www.ganet.state.ga.us/services/ocode/ocgsearch.htm

Hawaii

572-1 Requisites of valid marriage contract. In order to make valid the marriage contract, which shall be only between a man and a woman, it shall be necessary that:
(1) The respective parties do not stand in relation to each other of ancestor and descendant of any degree whatsoever, brother and sister of the half as well as to the whole blood, uncle and niece, aunt and nephew, whether the relationship is the result of the issue of parents married or not married to each other;
707-741 Incest. (1) A person commits the offense of incest if the person commits an act of sexual penetration with another who is within the degrees of consanguinity or affinity within which marriage is prohibited.
(2) Incest is a class C felony. [L 1972, c 9, pt of 1; am L 1987, c 176, 1

http://www.capitol.hawaii.gov/site1/docs/docs.asp?press1=docs

Idaho

32-205. INCESTUOUS MARRIAGES. Marriages between parents and children,
ancestors and descendants of every degree, and between brothers and sisters
of the half (1/2) as well as the whole blood, and between uncles and
nieces, or aunts and nephews, are incestuous, and void from the beginning,
whether the relationship is legitimate or illegitimate.

32-206. MARRIAGES BETWEEN FIRST COUSINS. All marriages between first
cousins are prohibited.

18-6602. INCEST. Persons being within the degrees of consanguinity within which marriages are declared by law to be incestuous and void, who intermarry with each other, or who commit fornication or adultery with each other, are punishable by imprisonment in the state prison not exceeding ten (10) years.

http://www3.state.id.us/idstat/TOC/32002KTOC.html

Illinios

Sec. 212. Prohibited Marriages. (a) The following marriages are prohibited: (1) a marriage entered into prior to the dissolution of an earlier marriage of one of the parties; (2) a marriage between an ancestor and a descendant or between a brother and a sister, whether the relationship is by the half or the whole blood or by adoption; (3) a marriage between an uncle and a niece or between an aunt and a nephew, whether the relationship is by the half or the whole blood; (4) a marriage between cousins of the first degree; however, a marriage between first cousins is not prohibited if: (i) both parties are 50 years of age or older; or (ii) either party, at the time of application for a marriage license, presents for filing with the county clerk of the county in which the marriage is to be solemnized, a certificate signed by a licensed physician stating that the party to the proposed marriage is permanently and irreversibly sterile;

http://www.legis.state.il.us/ilcs/ch750/ch750act5articles/ch750act5artstoc.htm

Indiana

Sec. 2. Two (2) individuals may not marry each other if the individuals are more closely related than second cousins. However, two (2) individuals may marry each other if the individuals are:
(1) first cousins; and
(2) both at least sixty-five (65) years of age.

http://www.state.in.us/legislative/ic/code/title31/ar11/

Iowa

595.19 Void marriages.
1. Marriages between the following persons who are related by blood are void:
a. Between a man and his father'ssister, mother's sister,daughter,sister, son's daughter, daughter'sdaughter,brother's daughter,or sister's daughter.
b. Between a woman and her father's brother, mother's brother, son,brother, son's son, daughter's son,brother's son, or sister's son.
c. Between first cousins.

http://web.legis.state.ia.us/Code.html

Kansas

23-102. Incestuous marriages void. All marriages between parents and children, including grandparents and grandchildren of any degree, between brothers and sisters of the one half as well as the whole blood, and between uncles and nieces, aunts and nephews, and first cousins, are declared to be incestuous and absolutely void.
21-3602. Incest. Incest is marriage to or engaging in otherwise lawful sexual intercourse or sodomy, as defined by K.S.A. 21-3501 and amendments thereto, with a person who is 18 or more years of age and who is known to the offender to be related to the offender as any of the following biological relatives: parent, child, grandparent of any degree, grandchild of any degree, brother, sister, half-brother, half-sister, uncle, aunt, nephew or niece.

Incest is a severity level 10, person felony.

Aggravated incest. (a) Aggravated incest is: (1) Marriage to a person who is under 18 years of age and who is known to the offender to be related to the offender as any of the following biological, step or adoptive relatives: Child, grandchild of any degree, brother, sister, half-brother, half-sister, uncle, aunt, nephew or niece; or
(2) engaging in: (A) Otherwise lawful sexual intercourse or sodomy as defined by K.S.A. 21-3501 and amendments thereto; or (B) any lewd fondling, as described in subsection (a)(1) of K.S.A. 21-3503 and amendments thereto, with a person who is 16 or more years of age but under 18 years of age and who is known to the offender to be related to the offender as any of the following biological, step or adoptive relatives: Child, grandchild of any degree, brother, sister, half-brother, half-sister, uncle, aunt, nephew or niece.
(b) Aggravated incest as described in subsection (a)(2)(A) is a severity level 5, person felony. Aggravated incest as described in subsections (a)(1) and (a)(2)(B) is a severity level 7, person felony.

http://www.ink.org/public/legislative/statutes/statutes.cgi

Kentucky

402.010 Degree of relationship that will bar marriage

(1)No marriage shall be contracted between persons who are nearer of kin to each other by consangguinity, whether of the whole or half-blood than second cousins.
(2) Marriages prohibited by section (1) are incestuous and void.

530.020 Incest. (1) A person is guilty of incest when he has sexual intercourse or deviate sexual intercourse, as defined in KRS 510.010, with a person whom he knows to be an ancestor, descendant, brother, or sister. The relationships referred to herein include blood relationships of either the whole or half-blood without regard to legitimacy, relationship of parent and child by adoption, and relationship of stepparent and stepchild.

http://162.114.4.13/krs/402-00/CHAPTER.HTM
 

Louisiana
Art. 90. Impediments of relationship
The following persons, whether legitimate or illegitimate, may not contract marriage with each other:
Ascendants and descendants. Collaterals within the fourth degree, whether of the whole or of the half blood.
The impediment exists whether the persons are related by consanguinity or by adoption. Nevertheless, persons related by adoption, though not by blood, in the collateral line within the fourth degree may marry each other if they obtain judicial authorization in writing to do so.
Acts 1987, No. 886, 1, eff. Jan. 1, 1988.

78. Incest
A. Incest is the marriage to, or sexual intercourse with, any ascendant or descendant, brother or sister, uncle or niece, aunt or nephew, with knowledge of their relationship.
B. The relationship must be by consanguinity, but it is immaterial whether the parties to the act are legitimate or illegitimate or related to one another by the whole or half blood.
C. This Section shall not apply where one, not a resident of this state at the time of the celebration of his marriage, shall have contracted a marriage lawful at the place of celebration and shall thereafter have removed to this state.
D.(1) Whoever commits incest, where the crime is between an ascendant and descendant, or between brother and sister, shall be imprisoned at hard labor for not more than fifteen years.
(2) Whoever commits incest, where the crime is between uncle and niece, or aunt and nephew, shall be fined not more than one thousand dollars, or imprisoned, with or without hard labor, for not more than five years, or both.
Acts 1985, No. 706, 1.

http://www.legis.state.la.us/tsrs/search.htm

Maine

1997, c. 65, 3 (new).]

2. Prohibitions based on degrees of consanguinity; exceptions. This subsection
governs marriage between relatives.

A. A man may not marry his mother, grandmother, daughter, granddaughter, sister,
brother's daughter, sister's daughter, father's sister, mother's sister, the daughter of
his father's brother or sister or the daughter of his mother's brother or sister. A
woman may not marry her father, grandfather, son, grandson, brother, brother's son,
sister's son, father's brother, mother's brother, the son of her father's brother or sister
or the son of her mother's brother or sister. [1995, c. 694, Pt. B, 2 (new); Pt. E, 2
(aff).]

B. Notwithstanding paragraph A, a man may marry the daughter of his father's
brother or sister or the daughter of his mother's brother or sister, and a woman may
marry the son of her father's brother or sister or the son of her mother's brother or
sister as long as, pursuant to sections 651 and 652, the man or woman provides the
physician's certificate of genetic counseling. [1995, c. 694, Pt. B, 2 (new); Pt. E, 2
(aff).]

http://janus.state.me.us/legis/statutes/19-A/title19-Ach00sec0.html
 
 

Maryland

2-202.
(a) Any marriage performed in this State that is prohibited by this section is void.
(b) (1) A man may not marry his:
(i) grandmother;
(ii) mother;
(iii) daughter;
(iv) sister; or
(v) granddaughter.
(2) A woman may not marry her:
(i) grandfather;
(ii) father;
(iii) son;
(iv) brother; or
(v) grandson.
(3) An individual who violates any provision of this subsection is guilty of a misdemeanor and on conviction is subject to a fine of $1,500 or to permanent banishment from this State.
(c) (1) A man may not marry his:
(i) grandfather's wife;
(ii) wife's grandmother;
(iii) father's sister;
(iv) mother's sister;
(v) stepmother;
(vi) wife's mother;
(vii) wife's daughter;
(viii) son's wife;
(ix) grandson's wife;
(x) wife's granddaughter;
(xi) brother's daughter; or
(xii) sister's daughter.
(2) A woman may not marry her:
(i) grandmother's husband;
(ii) husband's grandfather;
(iii) father's brother;
(iv) mother's brother;
(v) stepfather;
(vi) husband's father;
(vii) husband's son;
(viii) daughter's husband;
(ix) husband's grandson;
(x) brother's son;
(xi) sister's son; or
(xii) granddaughter's husband.
(3) An individual who violates any provision of this subsection is guilty of a misdemeanor and on conviction is subject to a fine of $500.

http://mlis.state.md.us/cgi-win/web_statutes.exe

Massachusetts

Chapter 272: Section 17. Incestuous marriage or intercourse.
Section 17. Persons within the degrees of consanguinity within which marriages are prohibited or declared by law to be incestuous and void, who intermarry or have sexual intercourse with each other, shall be punished by imprisonment in the state prison for not more than twenty years or in jail for not more than two and one half years.
Chapter 207: Section 1. Marriage of man to certain relatives.
Section 1. No man shall marry his mother, grandmother, daughter, granddaughter, sister, stepmother, grandfather's wife, grandson's wife, wife's mother, wife's grandmother, wife's daughter, wife's granddaughter, brother's daughter, sister's daughter, father's sister or mother's sister.
Chapter 207: Section 2. Marriage of woman to certain relatives.
Section 2. No woman shall marry her father, grandfather, son, grandson, brother, stepfather, grandmother's husband, daughter's husband, granddaughter's husband, husband's grandfather, husband's son, husband's grandson, brother's son, sister's son, father's brother or mother's brother.

http://www.state.ma.us/legis/laws/mgl/index.htm

Michigan

Sec. 3. A man shall not marry his mother, sister, grandmother, daughter, granddaughter, stepmother, grandfather's wife, son's wife, grandson's wife, wife's mother, wife's grandmother, wife's daughter, wife's granddaughter, brother's daughter, sister's daughter, father's sister, mother's sister, or cousin of the first degree, or another man.
Sec. 4. A woman shall not marry her father, brother, grandfather, son, grandson, stepfather, grandmother's husband, daughter's husband, granddaughter's husband, husband's father, husband's grandfather, husband's son, husband's grandson, brother's son, sister's son, father's brother, mother's brother, or cousin of the first degree, or another woman.

http://www.michiganlegislature.org/law/GetObject.asp?objName=chap551

Minnesota

(2) a marriage between an ancestor and a descendant, or between a brother and a sister, whether the relationship is by the half or the whole blood or by adoption;
(3) a marriage between an uncle and a niece, between an aunt and a nephew, or between first cousins, whether the relationship is by the half or the whole blood, except as to marriages permitted by the established customs of aboriginal cultures; and

609.365 Incest.

Whoever has sexual intercourse with another nearer of kin
to the actor than first cousin, computed by rules of the civil
law, whether of the half or the whole blood, with knowledge of
the relationship, is guilty of incest and may be sentenced to
imprisonment for not more than ten years.

http://www.revisor.leg.state.mn.us/stats/517.html

Mississippi

(1) The son shall not marry his grandmother, his mother, or his stepmother; the brother his sister; the father his daughter, or his legally adopted daughter, or his grand-daughter; the son shall not marry the daughter of his father begotten of his stepmother, or his aunt, being his father's or mother's sister, nor shall the children of brother or sister, or brothers and sisters intermarry being first cousins by blood. The father shall not marry his son's widow; a man shall not marry his wife's daughter, or his wife's daughter's daughter, or his wife's son's daughter, or the daughter of his brother or sister; and the like prohibition shall extend to females in the same degrees. All marriages prohibited by this subsection are incestuous and void.

97-29-27. Incest; marriage within prohibited degrees.
If any person shall marry within the degrees prohibited by law, he shall be guilty of incest, and on conviction thereof he shall be fined five hundred dollars or imprisoned in the penitentiary not longer than ten years, or punished by both such fine and imprisonment, and such marriage shall be void.

97-29-9. Adultery and fornication;going out of state to marry.

If any persons, citizens or residents of this state, who are prohibited by the laws thereof from marrying, because of kindred, shall go out of this state for the purpose of marrying, and shall marry in any other state or country and return to this state and live together and cohabit as man and wife, or be guilty of a single act of copulation, they shall, on conviction, be punished, notwithstanding their marriage out of this state, by imprisonment in the penitentiary not longer than ten years, or be fined five hundred dollars, or both.

http://www.lexislawpublishing.com/Resources/

Missouri

451.020. All marriages between parents and children, including grandparents and grandchildren of every degree, between brothers and sisters of the half as well as the whole blood, between uncles and nieces, aunts and nephews, first cousins, and between persons who lack capacity to enter into a marriage contract, are presumptively void; and it shall be unlawful for any city, county or state official having authority to issue marriage licenses to issue such marriage licenses to the persons heretofore designated, and any such official who shall issue such licenses to the persons aforesaid knowing such persons to be within the prohibition of this section shall be deemed guilty of a misdemeanor; and this prohibition shall apply to persons born out of lawful wedlock as well as those in lawful wedlock. It shall be presumed that marriages between persons who lack capacity to enter into a marriage contract are prohibited unless the court having jurisdiction over such persons approves the marriage.

Incest.
568.020. 1. A person commits the crime of incest if he marries or purports to marry or engages in sexual intercourse or deviate sexual intercourse with a person he knows to be, without regard to legitimacy:
(1) His ancestor or descendant by blood or adoption; or
(2) His stepchild, while the marriage creating that relationship exists; or
(3) His brother or sister of the whole or half-blood; or
(4) His uncle, aunt, nephew or niece of the whole blood.
2. For purposes of this section:
(1) "Sexual intercourse" means any penetration, however slight, of the female sex organ by the male sex organ;
(2) "Deviate sexual intercourse" means any act of sexual gratification between persons not lawfully married to one another, involving the genitals of one person and the mouth, tongue or anus of another.
3. Incest is a class D felony.

http://www.moga.state.mo.us/STATUTES/C451.HTM

Montana

40-1-401. Prohibited marriages -- contracts. (1) The following marriages are prohibited:
(b) a marriage between an ancestor and a descendant or between a brother and a sister, whether the relationship is by the half or the whole blood, or between first cousins;
(c) a marriage between an uncle and a niece or between an aunt and a nephew, whether the relationship is by the half or the whole blood;

45-5-507. Incest.
(1) A person commits the offense of incest if the person knowingly marries, cohabits with, has sexual intercourse with, or has sexual contact, as defined in [...] with an ancestor, a descendant, a brother or sister of the whole or half blood, or any stepson or stepdaughter. The relationships referred to in this subsection include blood relationships without regard to legitimacy, relationships of parent and child by adoption, and relationships involving a stepson or stepdaughter.
(2) Consent is a defense under this section to incest with or upon a stepson or stepdaughter, but consent is ineffective if the victim is less than 18 years old.
(3) A person convicted of incest shall be punished by life imprisonment or by imprisonment in the state prison for a term not to exceed 100 years or be fined an amount not to exceed $50,000.
(4) If the victim is under 16 years of age and the offender is 3 or more years older than the victim or if the offender inflicts bodily injury upon anyone in the course of committing incest, the offender shall be punished by life imprisonment or by imprisonment in the state prison for a term of not less than 4 years or more than 100 years and may be fined not more than $50,000.

(5) In addition to any sentence imposed under subsection (3) or (4), after determining the financial resources and future ability of the offender to pay restitution as required by [...] the court shall require the offender, if able, to pay the victim's reasonable costs of counseling that result from the offense. The amount, method, and time of payment must be determined in the same manner as provided for in [...]

http://statedocs.msl.state.mt.us/cgi-bin/om_isapi.dll?clientID=5588&advquery=void%20marriages&infobase=mca_99.nfo&record={9E95}&softpage=Browse_Frame_Pg&x=51&y=15

North Carolina

51-3. Want of capacity; void and voidable marriages.
All marriages between any two persons nearer of kin than first cousins, or between double first cousins, or between a male person under 16 years of age and any female, or between a female person under 16 years of age and any male, or between persons either of whom has a husband or wife living at the time of such marriage, or between persons either of whom is at the time physically impotent, or between persons either of whom is at the time incapable of contracting from want of will or understanding, shall be void.
14-178. Incest between certain near relatives. The parties shall be guilty of a felony in all cases of carnal intercourse between (i) grandparent and grandchild, (ii) parent and child or stepchild or legally adopted child, or (iii) brother and sister of the half or whole blood. Every such offense is punishable as a Class F felony. (1879, c. 16, s. 1; Code, s. 1060; Rev., s. 3351; 1911, c. 16; C.S., s. 4337; 1965, c. 132; 1979, c. 760, s. 5; 1979, 2nd Sess., c. 1316, s. 47; 1981, c. 63, s. 1, c. 179, s. 14; 1993, c. 539, s. 1192; 1994, Ex. Sess., c. 24, s. 14(c).)

14-179. Incest between uncle and niece and nephew and aunt. In all cases of carnal intercourse between uncle and niece, and nephew and aunt, the parties shall be guilty of a Class 1 misdemeanor. (1879, c. 16, s. 2; Code, s. 1061; Rev., s. 3352; C.S., s. 4338; 1993, c. 539, s. 118; 1994, Ex. Sess., c. 24, s. 14(c).)
14-180. Repealed by Session Laws 1975, c. 402.
14-181, 14-182. Repealed by Session Laws 1973, c. 108, s. 4.

http://www.ncga.state.nc.us/statutes/statutes_in_html/chp0510.html

North Dakota

14-03-03 Void Marriages. The following marriages are incestuous and void:
1. Marriage between parents and children including grandparents of every degree
2. Marriage between brothers and sisters of the half as well as the whole blood
3. Marriage between uncles and nieces of the half as well as the whole blood
4. Marriage between aunts and nephews of the half as well as the whole blood
5. Marriage between first cousins of the half as well as the whole blood

This section applies to illigitimate as well as ligitimate children and relatives.

14-03-14. Marriage between white person and negro person void - Penalty. REPEALED BY S.L 1955
12.1-20-11 Incest. A person who intermarries, cohabits, or engages in a sexual act with another person related to him within a degree of consanquity within which marries are declared incestuous and void by section 14-03-03, knowing suck other person to be within said degree of relationship, is guilty of class C felony.

http://ranch.state.nd.us/LR/cencode/CCT14.pdf

Nebraska

42-103. Marriages; when void. Marriages are void (1) when either party has a husband or wife living at the time of the marriage, (2) when either party, at the time of marriage, is mentally incompetent to enter into the marriage relation, and (3) when the parties are related to each other as parent and child, grandparent and grandchild, brother and sister of half as well as whole blood, first cousins when of whole blood, uncle and niece, and aunt and nephew. This subdivision extends to children and relatives born out of wedlock as well as those born in wedlock.
28-703. Incest; penalty. (1) Any person who shall knowingly intermarry or engage in sexual penetration with any person who falls within the degrees of consanguinity set forth in section 28-702 or any person who engages in sexual penetration with his or her minor stepchild commits incest.

(2) Incest is a Class III felony.

(3)(a) For purposes of this section, the definitions found in section 28-318 shall be used.

(b) The testimony of a victim shall be entitled to the same weight as the testimony of victims of other crimes under this code.

http://lp.datamgt.com/nesl/

Nevada

NRS 122.020 Persons capable of marriage; consent of parent or guardian.
1. A male and a female person, at least 18 years of age, not nearer of kin than second cousins or cousins of the half blood, and not having a husband or wife living, may be joined in marriage.
NRS 201.180 Incest: Definition; penalty. Persons being within the degree of consanguinity within which marriages are declared by law to be incestuous and void, who intermarry with each other, or who commit fornication or adultery with each other, shall be punished for a category B felony by imprisonment in the state prison for a minimum term of not less than 2 years and a maximum term of not more than 10 years, and may be further punished by a fine of not more than $10,000.
[1911 C&P 193; RL 6458; NCL 10140]-(NRS A 1979, 1429; 1995, 1198)
http://www.leg.state.nv.us/NRS/index.htm

New Hampshire

457:1 Marriages Prohibited; Men. No man shall marry his mother, his father's sister, mother's sister, daughter, sister, son's daughter, daughter's daughter, brother's daughter, sister's daughter, father's brother's daughter, mother's brother's daughter, father's sister's daughter, mother's sister's daughter, or any other man.
457:2 Marriages Prohibited; Women. No woman shall marry her father, her father's brother, mother's brother, son, brother, son's son, daughter's son, brother's son, sister's son, father's brother's son, mother's brother's son, father's sister's son, mother's sister's son, or any other woman.

http://199.192.9.6/rsa/43/INDEX.HTM#Chapter 457

New Jersey
37:1-1. Certain marriages prohibited
A man shall not marry any of his ancestors or descendants, or his sister, or the daughter of his brother or sister, or the sister of his father or mother, whether such collateral kindred be of the whole or half blood. A woman shall not marry any of her ancestors or descendants, or her brother, or the son of her brother or sister, or the brother of her father or mother, whether such collateral kindred be of the whole or half blood. A marriage in violation of any of the foregoing provisions shall be absolutely void.

http://www.njleg.state.nj.us/html/statutes.htm

New Mexico

40-1-7. [Incestuous marriages.]
All marriages between relations and children, including grandfathers and grandchildren of all degrees, between half brothers and sisters, as also of full blood; between uncles and nieces, aunts and nephews, are hereby declared incestuous and absolutely void. This section shall extend to illegitimate as well as to legitimate children.

30-10-3. Incest.
Incest consists of knowingly intermarrying or having sexual intercourse with persons within the following degrees of consanguinity: parents and children including grandparents and grandchildren of every degree, brothers and sisters of the half as well as of the whole blood, uncles and nieces, aunts and nephews. Whoever commits incest is guilty of a third degree felony.

http://www.lexislawpublishing.com/sdCGI-BIN/om_isapi.dll?clientID=8465&hitsperheading=on&infobase=nmsa1978.NFO&jump=40-1-7&softpage=Document#JUMPDEST_40-1-7

New York

Sec. 5. Incestuous and void marriages. A marriage is incestuous and void whether the relatives are legitimate or illegitimate between either: 1. An ancestor and a descendant; 2. A brother and sister of either the whole or the half blood; 3. An uncle and niece or an aunt and nephew. If a marriage prohibited by the foregoing provisions of this section be solemnized it shall be void, and the parties thereto shall each be fined not less than fifty nor more than one hundred dollars and may, in the discretion of the court in addition to said fine, be imprisoned for a term not exceeding six months. Any person who shall knowingly and wilfully solemnize such marriage, or procure or aid in the solemnization of the same, shall be deemed guilty of a misdemeanor and shall be fined or imprisoned in like manner.

S 255.25 Incest. A person is guilty of incest when he or she marries or engages in sexual intercourse or deviate sexual intercourse with a person whom he or she knows to be related to him or her, either legitimately or out of wedlock, as an ancestor, descendant, brother or sister of either the whole or the half blood, uncle, aunt, nephew or niece. Incest is a class E felony.

http://www.findlaw.com/11stategov/ny/nycl.html

Ohio

3101.01 Persons who may be joined in marriage; minor to obtain consent.
Volume of Ohio Laws: 147 Bill Number: House Bill 408 Effective Date: 10-1-97 Text of Statute

Male persons of the age of eighteen years, and female persons of the age of sixteen years, not nearer of kin than second cousins, and not having a husband or wife living, may be joined in marriage.

http://onlinedocs.andersonpublishing.com/revisedcode/

Oklahoma

43-2. Marriages between ancestors and descendants of any degree, of a stepfather with a stepdaughter, stepmother with stepson, between uncles and nieces, aunts and nephews, except in cases where such relationship is only by marriage, between brothers and sisters of the half as well as the whole blood, and first cousins are declared to be incestuous, illegal and void, and are expressly prohibited. Provided, that any marriage of first cousins performed in another state authorizing such marriages, which is otherwise legal, is hereby recognized as valid and binding in this state as of the date of such marriage.

http://oklegal.onenet.net/statutes.basic.html

Oregon

106.020 Prohibited and void marriages. The following marriages are prohibited; and, if solemnized within this state, are absolutely void:

(1) When either party thereto had a wife or husband living at the time of such marriage.
(2) When the parties thereto are first cousins or any nearer of kin to each other, whether of the whole or half blood, whether by blood or adoption, computing by the rules of the civil law, except that when the parties are first cousins by adoption only, the marriage is not prohibited or void. [Amended by 1989 c.647 s.1]

SECTION 10. ORS 163.525 is amended to read: 163.525. (1) A person commits the crime of incest if the person marries or engages in sexual intercourse { - or deviate sexual intercourse - } with a person whom the person knows to be related to the person, either legitimately or illegitimately, as an ancestor, descendant or brother or sister of either the whole or half blood. (2) Incest is a Class C felony.

http://landru.leg.state.or.us/ors/

Pennsylvania

1703. Marriage within degree of consanguinity.
All marriages within the prohibited degrees of consanguinity as set forth in this part are voidable, but, when any of these marriages have not been dissolved during the lifetime of the parties, the unlawfulness of the marriage shall not be inquired into after the death of either of the parties to the marriage.
(e) Marriage to relatives.--No marriage license may be issued to applicants within the prohibited degrees of consanguinity which are as follows:
A man may not marry his mother.
A man may not marry the sister of his father.
A man may not marry the sister of his mother.
A man may not marry his sister.
A man may not marry his daughter.
A man may not marry the daughter of his son or daughter.
A man may not marry his first cousin.
A woman may not marry her father.
A woman may not marry the brother of her father.
A woman may not marry the brother of her mother.
A woman may not marry her brother.
A woman may not marry her son.
A woman may not marry the son of her son or daughter.
A woman may not marry her first cousin.

4302. Incest.
A person is guilty of incest, a felony of the second degree, if that person knowingly marries or cohabits or has sexual intercourse with an ancestor or descendant, a brother or sister of the whole or half blood or an uncle, aunt, nephew or niece of the whole blood. The relationships referred to in this section include blood relationships without regard to legitimacy, and relationship of parent and child by adoption.

http://members.aol.com/StatutesPA/23.html

Rhode Island

15-1-1 Men forbidden to marry kindred. No man shall marry his mother, grandmother, daughter, son's daughter, daughter's daughter, stepmother, grandfather's wife, son's wife, son's son's wife, daughter's son's wife, wife's mother, wife's grandmother, wife's daughter, wife's son's daughter, wife's daughter's daughter, sister, brother's daughter, sister's daughter, father's sister, or mother's sister.
15-1-2 Women forbidden to marry kindred. No woman shall marry her father, grandfather, son, son's son, daughter's son, stepfather, grandmother's husband, daughter's husband, son's daughter's husband, daughter's daughter's husband, husband's father, husband's grandfather, husband's son, husband's son's son, husband's daughter's son, brother, brother's son, sister's son, father's brother, or mother's brother.

15-1-3 Incestuous marriages void. If any man or woman shall intermarry within the degrees stated in 15-1-1 or 15-1-2, the marriage shall be null and void.
15-1-4 Marriages of kindred allowed by Jewish religion. The provisions of 15-1-1 to 15-1-3 shall not extend to, or in any way affect, any marriage which shall be solemnized among the Jews, within the degrees of affinity or consanguinity allowed by their religion.

http://www.rilin.state.ri.us/Statutes/TITLE15/INDEX.HTM

South Carolina

SECTION 20-1-10. Persons who may contract matrimony.
(B) No man shall marry his mother, grandmother, daughter, granddaughter, stepmother, sister, grandfather's wife, son's wife, grandson's wife, wife's mother, wife's grandmother, wife's daughter, wife's granddaughter, brother's daughter, sister's daughter, father's sister, mother's sister, or another man.
(C) No woman shall marry her father, grandfather, son, grandson, stepfather, brother, grandmother's husband, daughter's husband, granddaughter's husband, husband's father, husband's grandfather, husband's son, husband's grandson, brother's son, sister's son, father's brother, mother's brother, or another woman.
 

SECTION 16-15-20. Incest.
Any persons who shall have carnal intercourse with each other within the following degrees of relationship, to wit:
(1) A man with his mother, grandmother, daughter, granddaughter, stepmother, sister, grandfather's wife, son's wife, grandson's wife, wife's mother, wife's grandmother, wife's daughter, wife's granddaughter, brother's daughter, sister's daughter, father's sister or mother's sister; or
(2) A woman with her father, grandfather, son, grandson, stepfather, brother, grandmother's husband, daughter's husband, granddaughter's husband, husband's father, husband's grandfather, husband's son, husband's grandson, brother's son, sister's son, father's brother or mother's brother;
Shall be guilty of incest and shall be punished by a fine of not less than five hundred dollars or imprisonment not less than one year in the Penitentiary, or both such fine and imprisonment.

http://www.lpitr.state.sc.us/code/titl20.htm

South Dakota

25-1-6. Incestuous marriages void.

Marriages between parents and children, ancestors and descendants of every degree, and between brothers and sisters of the half as well as the whole blood, and between uncles and nieces, or aunts and nephews, and between cousins of the half as well as of the whole blood, are null and void from the beginning, whether the relationship is legitimate or illegitimate. The relationships provided for in this section include such relationships that arise through adoption.

22-22-19.1. Incest - Prohibited sexual contact - Felony.

Any person, fourteen years of age or older, who knowingly engages in sexual contact with another person, other than that person's spouse, if the other person is under the age of twenty-one and is within the degree of consanguinity or affinity within which marriages are by the laws of this state declared void pursuant to a charge brought pursuant to this section may be commenced at any time prior to the time the victim becomes age twenty-five or within seven years of the commission of the crime, whichever is longer.

http://www.lexislawpublishing.com/sdCGI-BIN/om_isapi.dll?clientID=2428&infobase=sdcode.NFO&softpage=browse_frame_pg

Tennessee

36-3-101. Prohibited degrees of relationship.

Marriage cannot be contracted with a lineal ancestor or descendant, nor the lineal ancestor or descendant of either parent, nor the child of a grandparent, nor the lineal descendants of husband or wife, as the case may be, nor the husband or wife of a parent or lineal descendant.

39-15-302. Incest.
(a) A person commits incest who engages in sexual penetration as defined in [..] with a person, knowing such person to be, without regard to legitimacy:
(1) The person's natural parent, child, grandparent, grandchild, uncle, aunt, nephew, niece, stepparent, stepchild, adoptive parent, adoptive child; or
(2) The person's brother or sister of the whole or half-blood or by adoption.
(b) Incest is a Class C felony.

http://www.lexislawpublishing.com/sdCGI-BIN/om_isapi.dll?clientID=1879&infobase=tncode.NFO&softpage=browse_frame_pg

Texas

SUBCHAPTER C. DECLARING A MARRIAGE VOID

Sec. 6.201. Consanguinity.

A marriage is void if one party to the marriage is related to the other as:

(1) an ancestor or descendant, by blood or adoption;

(2) a brother or sister, of the whole or half blood or by adoption;

(3) a parent's brother or sister, of the whole or half blood or by adoption; or

(4) a son or daughter of a brother or sister, of the whole or half blood or by adoption.

http://capitol.tlc.state.tx.us/statutes/statutes.html

Utah

30-1-1.   Incestuous marriages void.

     (1) The following marriages are incestuous and void from the beginning, whether the relationship is legitimate or illegitimate:
     (a) marriages between parents and children;
     (b) marriages between ancestors and descendants of every degree;
     (c) marriages between brothers and sisters of the half as well as the whole blood;
     (d) marriages between uncles and nieces or aunts and nephews;
     (e) marriages between first cousins, except as provided in Subsection (2); or
     (f) marriages between any persons related to each other within and not including the fifth degree of consanguinity computed
            according to the rules of the civil law, except as provided in Subsection (2).
     (2) First cousins may marry under the following circumstances:
     (a) both parties are 65 years of age or older; or
     (b) if both parties are 55 years of age or older, upon a finding by the district court, located in the district in which either
            party resides, that either party is unable to reproduce.
 

76-7-102.   Incest.
1) A person is guilty of incest when, under
circumstances not amounting to rape, rape of a
child or aggravated sexual assault, he has sexual
intercourse with a person whom he knows to be
an ancestor, descendant, brother, sister, uncle,
aunt, nephew, niece, or first cousin. The
relationships referred to herein include blood
relationships of the whole or half blood without
regard to legitimacy, relationship of parent and
child by adoption, and  relationship of stepparent
and stepchild while the marriage creating the
relationship of a stepparent  and stepchild exists.

      (2)    Incest is a felony of the third degree.

http://www.le.state.ut.us/~code/TITLE30/30_01.htm

Vermont

TITLE 15: Domestic Relations
CHAPTER 001: MARRIAGE

1. Man forbidden to marry relatives
A man shall not marry his mother, grandmother, daughter, granddaughter, sister, brother's daughter, sister's daughter, father's sister or mother's sister. (Amended 1975, No. 28, 1.)

2. Woman forbidden to marry relatives
A woman shall not marry her father, grandfather, son, grandson, brother, brother's son, sister's son, father's brother or mother's brother. (Amended 1975, No. 28, 2.)

3. Bar though marriage dissolved
If the relationship in those cases mentioned in sections 1 and 2 of this title is founded on a marriage, the prohibition shall continue in force notwithstanding the dissolution of such marriage by death or divorce, unless the divorce is for a cause which shows the marriage to have been originally unlawful or void.

5. Marriage entered into in another state
If a person residing and intending to continue to reside in this state is prohibited from contracting marriage under the laws of this state and such person goes into another state or country and there contracts a marriage prohibited and declared void by the laws of this state, such marriage shall be null and void for all purposes in this state.

205. Intermarriage of or fornication by persons prohibited to marry
Persons between whom marriages are prohibited by the laws of this state who intermarry or commit fornication with each other shall be imprisoned not more than five years or fined not more than $1,000.00, or both. (Amended 1981, No. 223 (Adj. Sess.), 16.)

http://www.leg.state.vt.us/statutes/statutes.htm

Virginia

20-38.1. Certain marriages prohibited.
(a) The following marriages are prohibited:
(1) A marriage entered into prior to the dissolution of an earlier marriage of one of the parties;
(2) A marriage between an ancestor and descendant, or between a brother and a sister, whether the relationship is by the half or the whole blood or by adoption;
(3) A marriage between an uncle and a niece or between an aunt and a nephew, whether the relationship is by the half or the whole blood.

20-40. Punishment for violation of such prohibition; leaving Commonwealth to avoid.
If any person marry in violation of 20-38.1 </cgi-bin/legp504.exe?000+cod+20-38.1> he shall be confined in jail not exceeding six months, or fined not exceeding $500, in the discretion of the jury. If any persons, resident in this Commonwealth, and within the degrees of relationship mentioned in that section, shall go out of this Commonwealth for the purpose of being married, and with the intention of returning, and be married out of it, and afterwards return to and reside in it, cohabiting as man and wife, they shall be punished as provided in this section, and the marriage shall be governed by the same law as if it had been solemnized in this Commonwealth. The fact of such cohabitation here shall be evidence of such marriage.

18.2-366. Adultery and fornication by persons forbidden to marry; incest.
A. Any person who commits adultery or fornication with any person whom he or she is forbidden by law to marry shall be guilty of a Class 1 misdemeanor except as provided by subsection B.
B. Any person who commits adultery or fornication with his daughter or granddaughter, or with her son or grandson, or her father or his mother, shall be guilty of a Class 5 felony. However, if a parent or grandparent commits adultery or fornication with his or her child or grandchild, and such child or grandchild is at least thirteen years of age but less than eighteen years of age at the time of the offense, such parent or grandparent shall be guilty of a Class 3 felony.

http://leg1.state.va.us/000/src.htm

Washington

RCW 26.04.020
Prohibited marriages.
(b) When the husband and wife are nearer of kin to each other than second cousins, whether of the whole or half blood computing by the rules of the civil law; or
(c) When the parties are persons other than a male and a female.
(2) It is unlawful for any man to marry his father's sister, mother's sister, daughter, sister, son's daughter, daughter's daughter, brother's daughter or sister's daughter; it is unlawful for any woman to marry her father's brother, mother's brother, son, brother, son's son, daughter's son, brother's son or sister's son.

RCW 9A.64.020
Incest.
(1) A person is guilty of incest in the first degree if he engages in sexual intercourse with a person whom he knows to be related to him, either legitimately or illegitimately, as an ancestor, descendant, brother, or sister of either the whole or the half blood.
(2) A person is guilty of incest in the second degree if he engages in sexual contact with a person whom he knows to be related to him, either legitimately or illegitimately, as an ancestor, descendant, brother, or sister of either the whole or the half blood.
(3) As used in this section, "descendant" includes stepchildren and adopted children under eighteen years of age.
 

http://leg1.state.va.us/000/src.htm

Wisconsin

765.21 Unlawful marriages void; validation. All marriages hereafter contracted in violation of 765.02, 765.03, 765.04, 765.16 [see below] shall be void, except as provided in [...] The parties to any such marriage may validate the marriage by complying with the requirements of

765.03(1)
(1) No marriage shall be contracted while either of the parties has a husband or wife living, nor between persons who are nearer of kin than 2nd cousins except that marriage may be contracted between first cousins where the female has attained the age of 55 years or where either party, at the time of application for a marriage license, submits an affidavit signed by a physician stating that either party is permanently sterile. Relationship under this section shall be computed by the rule of the civil law, whether the parties to the marriage are of the half or of the whole blood. A marriage may not be contracted if either party has such want of understanding as renders him or her incapable of assenting to marriage.

765.04(1)
(1) If any person residing and intending to continue to reside in this state who is disabled or prohibited from contracting marriage under the laws of this state goes into another state or country and there contracts a marriage prohibited or declared void under the laws of this state, such marriage shall be void for all purposes in this state with the same effect as though it had been entered into in this state.
 

(15) "Relative" means a parent, grandparent, stepparent, brother, sister, first cousin, nephew, niece, uncle or aunt. This relationship shall be by blood, marriage or adoption.

944.06 Incest. Whoever marries or has nonmarital sexual intercourse with a person he or she knows is a blood relative and such relative is in fact related in a degree within which the marriage of the parties is prohibited by the law of this state is guilty of a Class C felony.

http://www.legis.state.wi.us/rsb/weblinks.html

West Virginia

48-1-2. What relatives a man may not marry.
No man shall marry his mother, grandmother, sister, daughter, granddaughter, half sister, aunt, brother's daughter, sister's daughter, first cousin or double cousin: Provided, That for the purpose of this section cousin or double cousin shall not include persons whose relationship is created solely by adoption: Provided, however, That if it be necessary to open and examine the record of any adoption proceeding in the state to ascertain that a relationship of cousin or double cousin is created solely by adoption, then an application may be made to the circuit court wherein such proceeding was had, by the clerk of the county commission seeking to issue the marriage license, or either party applying for such license, to open such record and cause examination thereof. Upon such application, the judge shall examine the record confidentially and report to the clerk whether the record discloses any consanguinity prohibited by this section and may grant such other relief prayed for which may be proper under section four, article four of this chapter.

48-1-3. What relatives a woman may not marry.
No woman shall marry her father, grandfather, brother, son, grandson, half brother, uncle, brother's son, sister's son, first cousin or double cousin: Provided, That for the purpose of this section cousin or double cousin shall not include persons whose relationship is created solely by adoption: Provided, however, That if it be necessary to open and examine the record of any adoption proceeding in the state to ascertain that a relationship of cousin or double cousin is created solely by adoption, then an application may be made to the circuit court wherein such proceeding was had, by the clerk of the county commission seeking to issue the marriage license, or either party applying for such license, to open such record and cause examination thereof. Upon such application, the judge shall examine the record confidentially and report to the clerk whether the record discloses any consanguinity prohibited by this section and may grant such other relief prayed for which may be proper under section four, article four of this chapter.

48-1-4. Prohibition against marriage within certain degrees continues notwithstanding dissolution of marriage creating relationship.
In the cases mentioned in the two preceding sections, in which the relationship is founded on a marriage, the prohibition shall continue in force, notwithstanding the dissolution of such marriage by death or divorce, unless the divorce be for a cause which made the marriage, originally, unlawful or void.
 
 

Acts, 1974 Reg. Sess., Ch. 35.
61-8-12. Incest; penalty.
(a) For the purposes of this section:
(1) "Aunt" means the sister of a person's mother or father;
(2) "Brother" means the son of a person's mother or father;
(3) "Daughter" means a person's natural daughter, adoptive daughter or the daughter of a person's husband or wife;
(4) "Father" means a person's natural father, adoptive father or the husband of a person's mother;
(5) "Granddaughter" means the daughter of a person's son or daughter;
(6) "Grandfather" means the father of a person's father or mother;
(7) "Grandmother" means the mother of a person's father or mother;
(8) "Grandson" means the son of a person's son or daughter;
(9) "Mother" means a person's natural mother, adoptive mother or the wife of a person's father;
(10) "Niece" means the daughter of a person's brother or sister;
(11) "Nephew" means the son of a person's brother or sister;
(12) "Sexual intercourse" means any act between persons involving penetration, however slight, of the female sex organ by the male sex organ or involving contact between the sex organs of one person and the mouth or anus of another person;
(13) "Sexual intrusion" means any act between persons involving penetration, however slight, of the female sex organ or of the anus of any person by an object for the purpose of degrading or humiliating the person so penetrated or for gratifying the sexual desire of either party;
(14) "Sister" means the daughter of a person's father or mother;
(15) "Son" means a person's natural son, adoptive son or the son of a person's husband or wife; and
(16) "Uncle" means the brother of a person's father or mother.
(b) A person is guilty of incest when such person engages in sexual intercourse or sexual intrusion with his or her father, mother, brother, sister, daughter, son, grandfather, grandmother, grandson, granddaughter, nephew, niece, uncle or aunt.
(c) Any person who violates the provisions of this section shall be guilty of a felony, and, upon conviction thereof, shall be imprisoned in the penitentiary not less than five years nor more than fifteen years, or fined not less than five hundred dollars nor more than five thousand dollars and imprisoned in the penitentiary not less than five years nor more than fifteen years.
(d) In addition to any penalty provided under this section and any restitution which may be ordered by the court under article eleven-a of this chapter, the court may order any person convicted under the provisions of this section where the victim is a minor to pay all or any portion of the cost of medical, psychological or psychiatric treatment of the victim, the need for which results from the act or acts for which the person is convicted, whether or not the victim is considered to have sustained bodily injury.
(e) In any case where a person is convicted of an offense described herein against a child and further has or may have custodial, visitation or other parental rights to the child, the court shall find that the person is an abusing parent within the meaning of article six, chapter forty-nine of this code, and shall take such further action in accord with the provisions of said article.
61-8-13. Incest; limits on interviews of children eleven years old or less; evidence.
(a) In any prosecution under the provisions of section twelve of this article, the court may provide by rule for reasonable limits on the number of interviews to which a victim who is eleven years old or less must submit for law-enforcement or discovery purposes. To the extent possible the rule shall protect the mental and emotional health of the child from the psychological damage of repeated interrogation and at the same time preserve the rights of the public and the defendant.
(b) At any stage of the proceedings, in any prosecution under this article, the court may permit a child who is eleven years old or less to use anatomically correct dolls, mannequins or drawings to assist such child in testifying.
(c) In any prosecution under this article in which the victim's lack of consent is based solely on the incapacity to consent because such victim was below a critical age, evidence of specific instances of the victim's sexual conduct, opinion evidence of the victim's sexual conduct and reputation evidence of the victim's sexual conduct shall not be admissible. In any other prosecution under this article, evidence of specific instances of the victim's prior sexual conduct with the defendant shall be admissible on the issue of consent: Provided, That such evidence heard first out of the presence of the jury is found by the judge to be relevant.
(d) In any prosecution under this article evidence of specific instances of the victim's sexual conduct with persons other than the defendant, opinion evidence of the victim's sexual conduct and reputation evidence of the victim's sexual conduct shall not be admissible: Provided, That such evidence shall be admissible solely for the purpose of impeaching credibility, if the victim first makes his or her previous sexual conduct an issue in the trial by introducing evidence with respect thereto.
(e) In any prosecution under this article, neither age nor mental capacity of the victim shall preclude the victim from testifying.

http://www.legis.state.wv.us/Code/toc.html

Wyoming

20-2-101. Void and voidable marriages defined; annulments.
[...]
(iii) When the parties stand in the relation to each other of parent and child, grandparent and grandchild, brother and sister of half or whole blood, uncle and niece, aunt and nephew, or first cousins, whether either party is illegitimate. This paragraph does not apply to persons not related by consanguinity.
6-4-402. Incest; penalties; disclosure or publication of identifying information; "minor victim".
(a) A person is guilty of incest if he knowingly commits sexual intrusion, as defined by W.S. 6-2-301(a)(vii), or sexual contact, as defined by W.S. 6-2-301(a)(vi), with an ancestor or descendant or a brother or sister of the whole or half blood. The relationships referred to herein include relationships of:
(i) Parent and child by adoption;
(ii) Blood relationships without regard to legitimacy; and
(iii) Stepparent and stepchild.
(b) Incest is a felony punishable by imprisonment for not more than five (5) years, a fine of not more than five thousand dollars ($5,000.00), or both.
(c) Prior to the filing of an information or indictment charging a violation under this section, neither the name of the person accused or the victim nor any other information reasonably likely to disclose their identity shall be released or negligently allowed to be released to the public by any public employee, except as authorized by the judge or justice with jurisdiction over the criminal charges. The name of the person accused may be released to the public to aid or facilitate an arrest.
(d) After the filing of an information or indictment and upon the request of a minor victim or another acting on behalf of a minor victim, the trial court may, to the extent necessary to protect the welfare of the minor victim, restrict the disclosure or publication of information reasonably likely to identify the minor victim.
(e) Any person who willfully violates subsection (c) or (d) of this section or who willfully neglects or refuses to obey any court order made pursuant thereto is guilty of contempt and, upon conviction, shall be fined not more than seven hundred fifty dollars ($750.00) or be imprisoned in the county jail not more than ninety (90) days, or both.
(f) A release of a name or other information to the public in violation of the proscriptions of subsection (c) or (d) of this section shall not stand as a bar to the prosecution of a defendant nor be grounds for dismissal of any charges against a defendant.
(g) As used in this section, "minor victim" means a person under the age of eighteen (18) years.

http://legisweb.state.wy.us/titles/20titles/sub20.htm