Incest is marriage or sexual relations between close relatives. The criminal offense of incest may also be known as prohibited sexual conduct. Laws vary from state to state, but incest laws generally prohibit marriage or sexual relations between (1) a person’s ancestor or descendant by blood or adoption; (2) a person’s current or former stepchild or stepparent; (3) a person’s parent’s brother or sister of the whole or half blood; (4) a person’s brother or sister of the whole or half blood or by adoption; (5) the children of a person’s brother or sister of the whole or half blood, or by adoption; or (6) the son or daughter of a person’s aunt or uncle of the whole or half blood or by adoption.

Lack of consent to sexual relations between such relatives is not an element of the crime, and persons may be guilty of the crime even if both parties consented.

Laws regarding incest or prohibited sexual contact vary from state to state and are generally located in a state’s statutes—often in the penal or criminal code. The crime is a felony offense in many states, with potential punishment of significant jail or prison time.

In New Mexico, incest is defined as knowingly engaging in sexual intercourse or sexual contact with a relative within a degree of consanguinity that is prohibited by law. Under New Mexico law, incest is a third-degree felony. The prohibited degrees of consanguinity include ancestors, descendants, full or half siblings, and certain relatives by marriage or adoption, such as a parent's sibling or the child of a sibling. Consent is not a defense to a charge of incest, meaning that the crime can be prosecuted even if both parties consented to the sexual relationship. The penalties for a conviction of incest in New Mexico can include imprisonment and may have severe long-term consequences, including registration as a sex offender. It is important for individuals in New Mexico to be aware of these laws to avoid engaging in conduct that is considered a serious criminal offense.