One thing that the Vanity Fair article ignores is the fact that income is inversely proportional to child bearing.

According to the U.S. Bureau of the Census, in 2000, the fertility rate was highest (86.8 births per 1,000 women age 15 to 44 years) for women with annual family incomes below $10,000, second highest for women with family incomes between $25,000 and $30,000, and lowest in families with incomes of $75,000 and over (60.1 births per 1,000 women age 15 to 44 years).

If you assume a starting point with equal income distribution, the only variable being the number of children a family has, the result is pretty easy to see. Those who have fewer kids will be able to invest more per child, expend more attention and guidance per child (therefore maximizing the likelihood that the child will do better in school, etc.) and potentially leave a higher portion of an estate to each of them. Those kids who grow up with more would once again be expected to have a higher income and the cycle would continue. In a very few cycles, you would end up with huge wealth disparities, without any of the complicated reasons that are bandied about.

The question is, what would cause the disparity in child bearing in the first place? And by the way, I’m not saying this as a justification for unequal income distribution. At all. I like population genetics (a field that has much in common with economics) and I wonder sometimes why these basic factors are ignored.