What happened
A new study found that people with a common gene variant who were breast-fed scored higher on IQ tests than those who were bottle-fed. About 90 percent of the 3,000 babies in the United Kingdom and New Zealand included in the study had the gene. Those who did and were breast-fed scored an average 7 points higher on IQ tests than their formula-fed counterparts. One member of the research team, psychologist Avshalom Caspi, said the findings should reshape the “nature vs. nurture” debate. “‘Nature via nurture’ might be a better catch phrase,” Caspi said.

What the commentators said
Terrific, said Jeremy Laurance in the Seattle Post-Intelligencer, along comes another study to “upset the consensus” and plunge us into another battle in the mommy wars. The last big study came out last year, and said that breastfed babies “were smarter because their mothers were.” This debate has been raging since 1929, when the first paper on the subject was published, and the latest conclusions are “not likely to be the last word on the subject.”

The “La Leche nazis” are sure to insist this is “more proof that if you don’t breastfeed 24/7 you are a Bad Mother,” said Sarah Vine in the London Times’ Alpha Mummy blog. “Not true.” For babies who don’t have the gene, “breastfeeding made no difference at all.” And maybe all babies will be better off if people just stop making new moms feel “manhandled” and “judged,” so they can focus on doing what they think is best for their children.

There’s no denying that this adds to “a substantial body of research on the benefits of breast milk,” said Brandon Keim in the Wired science blog. We still have a lot to learn about what determines intelligence, but “the findings suggest that nurture is every bit as important as nature.”