We recently learned regarding 7 mitvos of Bnei Noach, that while arayos is assur, certain relationships, which while prohibited for Jews, are allowed for goyim. One of those reltionships is a father with his daughter. It is mutar for a goy to have a relationship with his daughter
If so, why was it looked down upon when Lot slept with his daughters? It was mutar for him?
Rafi
(a) RABEINU YONAH in our Gemara asks your question. The CHAMRA VE'CHAYEI finds in this a strong basis for the ruling of the ME'IRI, who prohibits a Ben No'ach to his daughter l'Halachah.
(b) The RAMBAN (Bereishis 19:32) in the Chumash in fact asks this as a question on the actions of the daughters of No'ach. Why did the daughters of Lot feel it necessary to intoxicate their father before having children from him, if a Ben No'ach is permitted to his daughter. He answers:
1. They were Tzenu'os, and were embarrassed to approach their father outright. (Chazal in Nazir 23a disgraced Lot since he allowed himself to be intoxicated and since he lived with his daughters out of wedlock. The daughters, though, may have acted properly.)
2. Although it was indeed Mutar to bear children from one's daughter, it was considered an abominable act among the nations and was never done in practice. (Rav Chaim Paltiel (circa 1300) adds that after the Mabul, the Benei Noach accepted upon themselves to abstain from all close family members, even though they were permitted to them Halachically.)
(c) The CHAMRA V'CHAYEI answers that since Lot at the time considered himself a disciple and member of the house of Avraham, whom he emulated with regard to Hachnasas Orchim, he ought not to have allowed himself to act like a Ben No'ach by having relations with his daughters.
M. Kornfeld, D. Zupnik