In the age-old debate between nature and nurture, scientists studying breast-feeding and IQ have declared a tie.
The international team of psychologists, psychiatrists and geneticists wanted to know whether genes are primarily responsible for determining a person's intellect or if environment plays a dominant role. They decided to examine breast-feeding because studies had found that nutrients in breast milk boost babies' neurodevelopment and that children who were breast-fed tend to have higher IQs.
So they searched for a gene that was likely to help babies get an intelligence boost from breast milk. The team focused on FADS2 because it plays a crucial role in metabolizing the fatty acids DHA and ARA, which help neurons build connections in the developing brain. DHA and ARA are abundant in breast milk but have only recently been added to infant formula.
The study hinged on the fact that babies are born with one of three versions of FADS2. For children in two of those categories, those who were breast-fed scored an average of 6.8 points higher on IQ tests compared with children who were raised on formula, the researchers found. Breast-feeding didn't make a difference for the third group.