There are always biological factors at play, but this premise of "race" as applied by anyone ever is always basically mythological and not related to biological differences in a meaningful way that isn't (at the risk of sounding dismissive, for which I apologize up front) racist. Sickle cell is actually the perfect example of this. The people of Namibia and Angola look the same to me. They're even from neighboring countries. And yet their cultures are very different certainly, their languages are different, one has high sickle cell prevalence and the other does not... So are black people from Namibia and Angola the same race if they don't have that genetic variation in common? What about other genetic things they don't share? What about the genetic things they share with white Americans? Are a black person from Tamil Nadu, a black person from Ethiopia, a black person from Mali, and a black person from Papua New Guinea the same "race"? They don't look the same to me aside from having dark skin. Are my black neighbors the same race? They also don't look the same aside from having dark skin. Probably none of them are carriers of sickle cell trait. Is there something identifiable they all share that they don't also often share with white populations?