Leviticus 18:11
You must not have sexual relations with the daughter of your father's wife, born to your father; she is your sister.

Leviticus 18:13
You must not have sexual relations with your mother's sister, for she is your mother's close relative.

Leviticus 20:19
You must not have sexual relations with the sister of your mother or your father, for it is exposing one's own kin; both shall bear their iniquity.