A person is guilty of incest in the third degree when he or she marries or engages in vaginal sexual contact, oral sexual contact or anal sexual contact with a person whom he or she knows to be related to him or her, whether through marriage or not, as an ancestor, descendant, brother or sister of either the whole or the half blood, uncle, aunt, nephew or niece. Incest in the third degree is a class E felony.
New York Legal Code