פירוש על קידושין 35:2

The fact that God uses the word inheritance in the context of Esau’s descendants implies to R. Hiyya b. Abin, that non-Jews inherit from their father’s from biblical law.

The problem with Esau is that it is unclear whether he is considered a Gentile or an apostate Israelite. After all, his father was Jacob. Lot, on the other hand, is clearly not from Abraham’s line and therefore the fact that his descendants receive an inheritance proves that Gentiles inherit from their fathers.