Genesis 19:30-38

Afterward Lot left Zoar because he was afraid of the people there, and he went to live in a cave in the mountains with his two daughters. One day the older daughter said to her sister, “There are no men left anywhere in this entire area, so we can’t get married like everyone else. And our father will soon be too old to have children. Come, let’s get him drunk with wine, and then we will have sex with him. That way we will preserve our family line through our father.” So that night they got him drunk with wine, and the older daughter went in and had intercourse with her father. He was unaware of her lying down or getting up again. The next morning the older daughter said to her younger sister, “I had sex with our father last night. Let’s get him drunk with wine again tonight, and you go in and have sex with him. That way we will preserve our family line through our father.” So that night they got him drunk with wine again, and the younger daughter went in and had intercourse with him. As before, he was unaware of her lying down or getting up again. As a result, both of Lot’s daughters became pregnant by their own father. When the older daughter gave birth to a son, she named him Moab. He became the ancestor of the nation now known as the Moabites. When the younger daughter gave birth to a son, she named him Ben-ammi. He became the ancestor of the nation now known as the Ammonites.