'Smart Genes' Prove Elusive

Scientists looking for the genes underlying intelligence are in for a slog. One of the largest, most rigorous genetic studies of human cognition1 has turned up inconclusive findings, and experts concede that they will probably need to scour the genomes of more than 1 million people to confidently identify even a small genetic influence on intelligence and other behavioural traits.

Studies of twins have repeatedly confirmed a genetic basis for intelligence, personality and other aspects of behaviour. But efforts to link IQ to specific variations in DNA have led to a slew of irreproducible results. Critics have alleged that some of these studies' methods were marred by wishful thinking and shoddy statistics. A sobering editorial in the January 2012 issue of Behavior Genetics2 declared that “it now seems likely that many of the published findings of the last decade are wrong or misleading and have not contributed to real advances in knowledge”.

In 2011, an international collaboration of researchers launched an effort to bring more rigour to studies of how genes contribute to behaviour. The group, called the...