Over the past generation, members of the college-educated class have become amazingly good at making sure their children retain their privileged status. They have also become devastatingly good at making sure the children of other classes have limited chances to join their ranks.

How they’ve managed to do the first task — giving their own children a leg up — is pretty obvious. It’s the pediacracy, stupid. Over the past few decades, upper-middle-class Americans have embraced behavior codes that put cultivating successful children at the center of life. As soon as they get money, they turn it into investments in their kids.

Upper-middle-class moms have the means and the maternity leaves to breast-feed their babies at much higher rates than high school-educated moms, and for much longer periods.

Upper-middle-class parents have the means to spend two to three times more time with their preschool children than less affluent parents. Since 1996, education expenditures among the affluent have increased by almost 300 percent, while education spending among every other group is basically flat.