Genes, Breastfeeding and IQ
Studies on intelligence and breastfeeding have come up with conflicting results. The major question has been whether the results have been skewed because more educated or more affluent mothers were more likely to breastfeed.
A new study by colleagues in London, New Zealand and here in the United States has just been published in the Proceedings of the National Academies of Sciences and indicates that a single gene influences whether breastfeeding improves a child’s intelligence.
The gene in which the researchers were interested is a fatty acid delta desaturase – FADS2 – that is involved in the genetic control of fatty acid pathways. Children with one version of the FADS2 gene scored seven points higher in IQ tests if they were breastfed, but breastfeeding had no effect on the IQ of children with a different version of the gene.
Researchers at the Institute of Psychiatry, Kings College London, used data from two previous studies of breast-fed infants in Britain and New Zealand that had involved more than 3,000 children. IQ was measured at various points between the ages of five and 13 years in the studies. The only thing that we do not know is exactly how long the children were breastfed.
This is yet another study to show us why the nature/nurture debate needs a radical re-think. Nutrition and genetics act together. People have been arguing about the roots of intelligence for at least a hundred years, and this research shows nature working via nurture to create better outcomes.
Around 90% of people carry the version of the gene that was associated with better IQ scores in breastfed children. We do not know if there are any ethnic differences in those numbers, but there may be.
And that seven point difference in IQ? It s not going to determine how well someone is going to do in life, but in school it might be enough to put the child in the top third of the class.