I noticed you posted a graph comparing the genetic differences between Europeans and Africans, but I think that graph was misleading. Genetically, the differences between most Africans (excluding North Africans) and the rest of the world is pretty distant:[
As you can see on this graph, there's not much of a genetic difference between an Italian, a Danish and an Iranian, but there's a substantial difference between them and a West African or them and a Japanese or them and an Indonesian:
Basically ethnicity in a genetic sense is like a spectrum so neighboring countries regardless of culture and ethnicity will have much more in common with each other than with people at another continent.