The people with the infinite family tree were all white and the stupid people in the future were mostly white too. Not want to neglect your statements about zipcode and whereabouts of your upbringing are more important than your DNA in how your IQ is. But the movie isn't making that statement either, IIRC. It's just saying that the people who could give their kids the "best" start in life, because they already would now how to not raise their kids in self-inflicted immaturity, aren't procreating. But I don't think that this is factual.