Leviticus 18:6
You may not have sex connection with anyone who is a near relation: I am the Lord.
Leviticus 18:7-19
You may not have sex relations with your father or your mother: she is your mother, you may not take her.
Leviticus 20:11-12
And the man who has sex relations with his father's wife has put shame on his father: the two of them are to be put to death; their blood will be on them.
Leviticus 20:17-21
And if a man takes his sister, daughter of his father or his mother, and has sex relations with her and she with him, it is an act of shame: they are to be cut off before the children of their people; he has had sex relations with his sister, and his sin will be on him.