Leviticus 18:6-9

“None of you shall approach any one of his close relatives to uncover nakedness. I am the LORD. You shall not uncover the nakedness of your father, which is the nakedness of your mother; she is your mother, you shall not uncover her nakedness. You shall not uncover the nakedness of your father’s wife; it is your father’s nakedness. You shall not uncover the nakedness of your sister, your father’s daughter or your mother’s daughter, whether brought up in the family or in another home.