Leviticus 20:19-21

19“ ‘Do not have sexual relations with the sister of either your mother or your father, for that would dishonor a close relative; both of you would be held responsible.

20“ ‘If a man has sexual relations with his aunt, he has dishonored his uncle. They will be held responsible; they will die childless.

21“ ‘If a man marries his brother’s wife, it is an act of impurity; he has dishonored his brother. They will be childless.