Leviticus 18:9-11

9You must not have sexual intercourse with your sister, whether she is your father’s daughter or your mother’s daughter, whether she is born in the same household or born outside it; you must not have sexual intercourse with either of them.

10You must not expose the nakedness of your son’s daughter or your daughter’s daughter by having sexual intercourse with them, because they are your own nakedness.

11You must not have sexual intercourse with the daughter of your father’s wife born of your father; she is your sister. You must not have intercourse with her.