From a washingtonpost.com article* (on a completely different subject, with no links to the study it refers to):

"A recent study by Scottish researchers asked whether the higher IQs seen in breast-fed children are the result of the breast milk they got or some other factor. By comparing the IQs of sibling pairs in which one was breast-fed and the other not, it found that breast milk is irrelevant to IQ and that the mother's IQ explains both the decision to breast-feed and her children's IQ."

A few questions:

Does the raw data in the study mentioned above come from the study in the Slate article we're all talking about, or somewhere else?

Are its authors just shills for the formula industry, as Isonomist may suspect? (Don't kill me, Iso; I just included this bit to show that I didn't come up with the idea on my own. Credit where credit is due and so forth.)

A cursory Google search comes up empty for links to the actual study. Would anyone care to attempt running down such a link and posting it here?

* The article "Study Debunks Theory On Teen Sex, Delinquency" goes on to say that: "Similar re-analyses have begun to undermine other conventional notions about health." This is followed by the quote at the top of my post, and then further examples of such notions about health. (link via Saletan, 2nd item on page as of this writing)