Charles Ellicott Commentary Leviticus 18:7

"The nakedness of thy father, even the nakedness of thy mother, shalt thou not uncover: she is thy mother; thou shalt not uncover her nakedness." — Leviticus 18:7 (ASV)

The nakedness of your father, or the nakedness of your mother. —The rendering of the Authorized Version is based upon the interpretation which prevailed during the second Temple, according to which this injunction is addressed both to the daughter and the son. The daughter must not marry or have sexual relations with the father, nor the son with the mother.

Hence the Chaldee Version of Jonathan translates it, “the woman shall not lie with her father, and the man shall not lie with his mother.” Accordingly, the case here contemplated is that of Lot’s daughters (Genesis 19:31–38). This passage may, however, be translated literally, the nakedness of your father, and the nakedness of your mother you shall not uncover. That is, they being both one flesh, the nakedness of the one is the nakedness of the other. Among the Persians and other eastern nations, marriage between son and mother was allowed.