BBC NEWS | Health | Gene 'links breastfeeding to IQ': "The study was done on infants in Britain and New Zealand, we aren't given any ethnicity data. I'm assuming these numbers apply only to "euros" for now.
Children with one version of the FADS2 gene scored seven points higher in IQ tests if they were breastfed.
But the Proceedings of the National Academy of Sciences study found breastfeeding had no effect on the IQ of children with a different version.
The gene in question helps break down fatty acids from the diet, which have been linked with brain development.
Seven points difference is enough to put the child in the top third of the class, the researchers said.
Some 90% of people carry the version of the gene which was associated with better IQ scores in breastfed children.
It's such an extraordinary result, with so many implications, we need to be cautious. It would be interesting to read the PNAS letter page next month.
It is worth noting that most children adopted as infants, or placed in orphanages, are not breastfed.