'Son's' in the Bible

You 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.

You must not have sexual intercourse with your daughter-in-law; she is your son's wife. You must not have intercourse with her.

You must not have sexual intercourse with both a woman and her daughter; you must not take as wife either her son's daughter or her daughter's daughter to have intercourse with them. They are closely related to her -- it is lewdness.