Genesis 19:33-38

That night they got their father to drink wine, and the older daughter went in and slept with him. He was not aware of it when she lay down or when she got up. The next day the older daughter said to the younger, “Last night I slept with my father. Let’s get him to drink wine again tonight, and you go in and sleep with him so we can preserve our family line through our father.” So they got their father to drink wine that night also, and the younger daughter went in and slept with him. Again he was not aware of it when she lay down or when she got up. So both of Lot’s daughters became pregnant by their father. The older daughter had a son, and she named him Moab; he is the father of the Moabites of today. The younger daughter also had a son, and she named him Ben-Ammi; he is the father of the Ammonites of today.