Kinship and Incest Prohibitions
Where this fits in the story: Genesis family narratives contain several unions and kinship situations that later Torah regulates more tightly; those narratives are background, not proof that every patriarchal action was normative.
Where Scripture takes it next: 1 Corinthians 5:1–5 — Very Strong. Paul's outrage that a man has his father's wife strongly corresponds to Leviticus 18:8/20:11 and Deuteronomic parallels.
Evidence boundary: No one-to-one Christological meaning should be assigned to the prohibited kinship degrees.