MIDRASH · AGGADAH

Lot and his two daughters left Zoar and settled in the mountains, for he was afraid to stay in Zoar. He and his two daughters lived in a cave. One day the older daughter said to the younger, “Our father is old, and there is no man around here to give us children—as is the custom all over the earth. Let’s get our father to drink wine and then sleep with him and preserve our family line through our father.”
**Extract taken from: https://www.biblegateway.com/passage/?search=Genesis%2019:30-38&version=NIV