Freakonomics posits that children born later in the year are not as strong, mentally and physically, and do worse in life due to fewer opportunities in school and athletics and elsewhere. This article in the Times about the exclusivity of the Dalton School, and its powerful admission director, seems to confirm/reject this view:

Summer birthdays need not apply. (“No!” [the admissions director] said excitedly. “The school is filled with summer birthdays!”)

There’s also this.

As admissions director since 1996 at the Dalton School on the Upper East Side, Ms. Krents decides each year which of the city’s supply of high-achieving 4-year-olds get the privilege of attending one of the nation’s best-regarded kindergartens, which costs $36,970 a year. Because many people believe admission to be a golden ticket leading to the Ivy League and a successful life beyond, and because of the increasingly bad math of private-school admissions in Manhattan, a kind of Babby Krents mythology has developed in certain precincts.

Successful life? Any data to support that?

H/T Militza