Leviticus 20:17, 19-20

‘If a man takes his sister, his father’s daughter or his mother’s daughter, so that he sees her nakedness and she sees his nakedness, it is a disgrace; and they shall be cut off in the sight of the sons of their people. He has uncovered his sister’s nakedness; he bears [responsibility for] his guilt.

You shall not uncover the nakedness of (have intimate relations with) your mother’s sister or your father’s sister, for such a one has uncovered his blood relative; they will bear their guilt. If there is a man who lies [intimately] with his uncle’s wife, he has uncovered his uncle’s nakedness; they will bear their sin. They will die childless.