Earlier quoted context omitted.
If the deficiency is not the result of previous racism, what is it the result of?
Take a completely random sampling of 1 million people from populations all across the world. And in fact, take them from the day of birth to avoid any sort of early biases (actually 'harbor' the parents from the day of conception to avoid any sort of prenatal differences). And now put all of these million people on a completely homogenous and equally fertile chunk of land on an island. Raise each and every single one…
I would. South Koreans are 2-3 inches taller than North Koreans, plus a miriad of other biological differences, in a relatively short span of time. This is for the same ethnicity, yet alone race.
For me, that alone is proof we are much more similar than we think, and environmental factors, which your hypothetical scenario accounts for perfectly, has a much greater impact on us compared to genetics.
Which is why, for perfectly randomly selected humans raised identically for 200 years, I would not expect significant differences.