Leviticus 18:8

6None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the LORD.

7The nakedness of thy father, or the nakedness of thy mother, shalt thou not uncover: she is thy mother; thou shalt not uncover her nakedness.

8The nakedness of thy father’s wife shalt thou not uncover: it is thy father’s nakedness.

9The nakedness of thy sister, the daughter of thy father, or daughter of thy mother, whether she be born at home, or born abroad, even their nakedness thou shalt not uncover.

10The nakedness of thy son’s daughter, or of thy daughter’s daughter, even their nakedness thou shalt not uncover: for theirs is thine own nakedness.