Genesis 19:35-38 English Standard Version (ESV)

35. So they made their father drink wine that night also. And the younger arose and lay with him, and he did not know when she lay down or when she arose.

36. Thus both the daughters of Lot became pregnant by their father.

37. The firstborn bore a son and called his name Moab. He is the father of the Moabites to this day.

38. The younger also bore a son and called his name Ben-ammi. He is the father of the Ammonites to this day.

Genesis 19