Leviticus 20:17-21

“ ‘If a man marries his sister, the daughter of either his father or his mother, and they have sexual relations, it is a disgrace. They are to be publicly removed from their people. He has dishonored his sister and will be held responsible. “ ‘If a man has sexual relations with a woman during her monthly period, he has exposed the source of her flow, and she has also uncovered it. Both of them are to be cut off from their people. “ ‘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. “ ‘If a man has sexual relations with his aunt, he has dishonored his uncle. They will be held responsible; they will die childless. “ ‘If a man marries his brother’s wife, it is an act of impurity; he has dishonored his brother. They will be childless.