Leviticus 20:19-21

19A man must not have sex with his mother's sister or with his father's sister. They are both doing a wrong thing. They are taking away the family's honour. Their sin causes their punishment.

20A man is sinning if he has sex with his aunt. He is taking away his father's brother's honour. They will have no children.

21It makes the people unclean if a man marries his brother's wife. He has taken away his brother's honour. They will not have any children.