I often wonder why people invoke racism so often when it comes to these issues when the reality is... disadvantaged white kids often fare pretty poorly too. If one of your strongest indicators, do you really need race to explain why, generation after generation, racial dmeographics shift less than we "would like".
Yes the smartest in this society are probably mostly a bunch of white guys. Not because being white makes you better, or smarter, but because there are more white people who can give their children the opportunity to advance. Which isn't to say that being white people gave them that ability, but just that, the "initial condition" that we started with has done more to influence the outcome than we want to give it credit.
In short, I often feel racism is used as an excuse to deny the lack of real mobility within society....because if you don't think race/genetics is a major factor, then how do you explain the "lack of progress" along racial lines, if there is very high mobility? Seems to me it may be the lack of real mobility.
The lack of real mobility is a myth. I can say this because I come from a family that emigrated and came to the United States and started off on welfare, living in government projects, and going to very poorly supported schools. What made the difference for me were parents to valued education and pushed their kids to go beyond what was considered average. They convinced me, my siblings, and themselves, that the government handouts were temporary aids for us, and that continuing to live off the government when we have the ability to eventually make it on our own is shameful. My parents were farmers and made it as far as completing elementary school back in their homeland. So it isn't as if they had a great start, either. Yet my siblings and I, on the other hand, completed college, and I completed my Ph. D. in mathematics -- and we all went through public schools prior to college. If I were an exception, then we might call it "lack of mobility." The problem I see is that our government has made it too easy for those who have to rely on its social programs to do it for so long. For many, it is much easier to accept a very modest, but not-uncomfortable lifestyle of welfare and food stamps rather than to make an honest effort to move out of their current conditions.
Many immigrants who come to the US will have very similar stories of how they or their parents moved to the US with hopes of finding better opportunities. They often come from places where the conditions are so terrible that even the living in government projects and relying on the US welfare system is heavenly in comparison. Yet they do not fall into the welfare trap and eventually contribute to society like the rest of US citizens who were born and raised here. What they have that a lot of folks who are "stuck on welfare" is a drive. In my own parents' case, what drove them was their belief that if they could escape a communist government (that sought to execute anyone who defied it) by risking everything on a 2-piston boat set off into unknown waters, then they can certainly get out of welfare. This drive is lacking in a lot of families who are currently relying on government programs (I'm referring to families in which welfare reliance occurs for generations).