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 York, incest is legally defined as sexual intercourse between close relatives who are not legally allowed to marry. Specifically, New York Penal Law sections 255.25, 255.26, and 255.27 address the crime of incest. These laws prohibit sexual relations or marriage between a parent and child, siblings (whether full or half-blood), and between an uncle or aunt with a niece or nephew. The law applies to both biological and adopted relationships. Incest is a felony in New York, and the severity of the charges can range from a class E to a class D felony, depending on the circumstances of the offense. Consent is not a defense to a charge of incest, meaning that even if both parties agree to the sexual relationship, they can still be prosecuted under the law. Convictions for incest can lead to significant prison time and other legal consequences.