Leviticus 18:10
Do not have sexual relations with your son's daughter or your daughter's daughter; that would dishonor you. The granddaughter prohibition extends the incest boundary downward in the generational structure: the son's daughter and the daughter's daughter are both protected. The dishonor framing — that would dishonor you — communicates that the incest prohibition protects not only the victim but the structural integrity of the family's generational relationships. The violation of the granddaughter relationship dishonors the covenant community's family structure.