One thing I have observed, particularly with Africans, is that if they grow up in Europe or if they grow up in Africa, there is a clear difference in the way they look when they are older, no matter their socio-economic status at that point.
Africa is the most diverse continent in terms of phenotype and genetics. For example: a West African, an Ethiopian and a San person have very little in common, physically speaking. It is a bit like saying African Americans are 'African' while most have admixtures with non-Africans.
Studies showed that Ethiopians (toward 50-55%) and Kushites (towards 35% for Bejas) have an important western asian input so they tend to look like transitional people.
Take a look at this link: http://www.traedays.com/blog/2006/06/are-you-thinking-what-i...
http://www.amazon.com/History-White-People-Irvin-Painter/dp/...
is that the ancient Greek authors were overwhelmingly of the opinion that what made different people groups different from one another was different living environments (climate and topography), with the Greeks of course thinking that their living environment tended to produce superior people.
You can see this clearly in london - it's pretty easy to observe which Africans migrated to England at perhaps age 10, vs those who were born and grew up in England.
What do I have to look for? How have you validated your observations? Got any examples?
Look at this link for example: http://www.traedays.com/blog/2006/06/are-you-thinking-what-i...