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)

You cannot find it because the authors asked that the Study be kept secret due to the numerous threats to their families from the local chapter of the La Leche League.

But I found it…. See below:

<link>

I am honest enough to admit it isan imperfect study; but it is no more imperfect than these other studies finding the opposite that do not truly control the "host of other factors" that affect IQ. Correlation - Causation confusion. .....I guess the formula industry not the only one shilling bad information. ..... the formula industry not the only one shilling bad information.

Your Saletan link really says it all as to how these kind of studies are speculative at best. Some are just sold harder than others.

Breast is best. But the IQ angle is likely bad science.

I dont' think IQ is as big a deal as social adjustment, but I'll kick this dead horse if you like. I'm not sure what the Scottish study methodology was, but it's unlikely that two given siblings will have equal IQs, so they're starting on bad footing. Also, often the eldest child has the highest IQ, regardless of which child is breastfed for however long, so unless they controlled for that phenomenon, plus environmental factors, like parental divorce in early childhood or family crises during test taking days, or loss of a family member or other upheavals, there's no way to know whether the data were interpreted correctly. I'd be curious. Like I said, I don't know how much breastfeeding absolutely makes a difference. I know from the science that it's better to some degree, on a whole cluster of issues, and I'll stick with that.

Interesting that the WAPO writer didn't realize that the study was done on American families, whether that's relevant or not.