Genesis 6:4
6:4 The Nephilim were on the earth in those days (and also after this) when the sons of God were having sexual relations with the daughters of humankind, who gave birth to their children. They were the mighty heroes of old, the famous men.
Genesis 38:16
38:16 He turned aside to her along the road and said, “Come on! I want to have sex with you.” (He did not realize it was his daughter-in-law.) She asked, “What will you give me in exchange for having sex with you?”