I believe the largest factor is genetic, and I also believe that most on the left also know this though they’d die before admit it. As a matter of fact, it suits them to a tee if it’s genetic, because that almost ensures that the gap will never be closed. As long as they can blame it on external factors while knowing otherwise, they have the perfect self-perpetuating excuse to redistribute wealth, diminish freedom, and hang millstones around the middle-classe’s neck while insulting them at the same time-while they wear their self-appointed halos well away from the dysfunction in high-priced gated communities with private schools or public schools with special admissions standards (I want to see who is squawking the loudest re the NAACP’s suit against schools like Stuyvesant, it might be quite telling).
BTW-RIP J Philippe Rushton October 2 2012
Read the best selling book "Guns, Germs and Steel" and you will see how you are looking at it wrong.. mostly cultural but other non genetic factors come into play.