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 Indiana, incest is defined as sexual intercourse or deviate sexual conduct with a relative who is at least 16 years old. The term 'relative' includes a person's ancestor, descendant, brother, sister, uncle, aunt, niece, nephew, parent, or step-parent, whether related by blood or adoption. Incest is considered a Level 5 felony under Indiana law, which can result in a significant prison sentence and fines. Consent is not a defense to a charge of incest, meaning that even if both parties agree to the sexual relationship, it is still considered a criminal offense. The relevant statutes can be found in the Indiana Code, specifically under the criminal or penal code sections dealing with sexual offenses.