200 years later, with a population that's multiplied several magnitudes over - would you expect to still see a completely equal people? I wouldn't. People are different. And each child that is born is different, even when born to the same parents. Even identical twins are no longer completely identical by the time of birth. These differences express themselves in different ways (and wow was that the most tautological statement ever), but the point is that I think it's highly illogical to expect to see equality.
Out of genuine curiosity, do you disagree?
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.
Their position paper on affirmative action is available here: https://www.aclu.org/other/affirmative-action-aclu-position-... and I think it illustrates not only their rationale, but the tone of their support for that philosophy.
Fair disclaimer that I am obviously opposed to this approach and have been cautiously skeptical of the ACLU for a while now.
I'm curious as to why you think that should necessarily be the case.
Unless one is going to argue that there are no genetic differences between individuals in the brain, it seems unlikely to me that different races don't have different brains in some fashion.
Sure that is a nearly impossible to accomplish considering how convoluted this equation is so we have to step back and it becomes a question of belief, and in this world of belief I can really only condense it into two categories.
1. If it exists, it doesn't matter 2. It exists and does matter ("does matter" in my mind precludes equality, one must be superior)
To me it is really a question of whether I personally choose be racist or not, racism being defined as "prejudice, discrimination, or antagonism directed against someone of a different race based on the belief that one's own race is superior".
I'm going to cut this short at that I do not believe someone can both believe a specific race is superior and act without prejudice. Again a lot of assumptions, but if wanted to keep going down the ladder of explanations I'd write an essay or a book.