Leviticus 18:6-9

“ ‘No one is to approach any close relative to have sexual relations. I am the LORD. “ ‘Do not dishonor your father by having sexual relations with your mother. She is your mother; do not have relations with her. “ ‘Do not have sexual relations with your father’s wife; that would dishonor your father. “ ‘Do not have sexual relations with your sister, either your father’s daughter or your mother’s daughter, whether she was born in the same home or elsewhere.