The so-called “warrior gene” has been associated with many traits, from gun carrying to gout (Image: Raul Arboleda/AFP/Getty Images)

The story of one gene epitomises popular misconceptions about how our DNA shapes us. But it can also teach some crucial lessons, says Ed Yong

Our tale begins two decades ago, when a group of Dutch women set out to find an explanation for the antisocial behaviour of the males in their family. As well as having learning difficulties, these men and boys were prone to outbursts of aggression and were racking up a list of serious offences, including arson, attempted rape and murder. Suspecting that the behaviour might be hereditary, the women approached geneticist Hans Brunner at the University Hospital in Nijmegen, the Netherlands. Eventually, in 1993, he tracked down the culprit: a defunct variant of a gene called monoamine oxidase A, or MAOA, located on the X chromosome.

Understandably, the announcement created a sensation. It was the first time a gene had been linked to human aggression – and MAOA seemed to be responsible for a history of violence stretching back five generations.

In the following years, evidence poured in to bolster the connection between MAOA and aggression. Then, in 2004, journalist Ann Gibbons sealed the link by giving MAOA the headline-friendly label “warrior gene”. The moniker stuck, raising the profile of MAOA, and at the same time fuelling misconceptions about how our behaviour is affected by our genetic make-up.

Unravelling the interaction between genes and behaviour is one of the toughest tasks in biology. The publication of the entire human genetic code, a decade ago, dispelled any illusions that …