It can also be seen, but to a different extent. An african that grows up in a city in a wealthy household seems to end up with a different sort of facial structure and skin than those who grow up in rural areas...and it never goes. However, the effect is far more pronounced among those who grow up abroad.
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.
It could just be the signs of malnutrition. 200 years ago there was about 1 foot difference between English nobles and Welch coal miners, because the nobles were better fed as children. It would probably show in a different facial structure too.
