Leviticus 20:17-21

17And if a man shall take his sister, his father’s daughter, or his mother’s daughter, and see her nakedness, and she see his nakedness; it is a shameful thing; and they shall be cut off in the sight of the children of their people: he hath uncovered his sister’s nakedness; he shall bear his iniquity. 18And if a man shall lie with a woman having her sickness, and shall uncover her nakedness; he hath made naked her fountain, and she hath uncovered the fountain of her blood: and both of them shall be cut off from among their people. 19And thou shalt not uncover the nakedness of thy mother’s sister, nor of thy father’s sister; for he hath made naked his near kin: they shall bear their iniquity. 20And if a man shall lie with his uncle’s wife, he hath uncovered his uncle’s nakedness: they shall bear their sin; they shall die childless. 21And if a man shall take his brother’s wife, it is impurity: he hath uncovered his brother’s nakedness; they shall be childless.