I read into your post the idea that it's training culture and not genetics that gets so many east africans into distance running success. Correct me if I'm wrong.
Seems unlikely to me. 100m and 200m is thoroughly dominated by New World West Africans.
Mid distance 400m to 1600m is pretty well split up between Africans, Whites, and East Asians. Whites actually seem to do well at 800m.
I don't really know, but it seems there's a ton of racial genetics at play in sport.
You see in olympic/power lifting it's dominated by nordics/baltics and persians. Considering global popularity it defies ideas about training culture.