Szabolcs Kéri, a scientist at Semmelweis University in Budapest, Hungary, examined a gene involved in brain development called neuregulin 1, which previous studies have linked to a slightly increased risk of schizophrenia. Moreover, a single DNA letter mutation that affects how much of the neuregulin 1 protein is made in the brain has been linked to psychosis, poor memory and sensitivity to criticism. About 50 per cent of healthy Europeans have one copy of this mutation, while 15 per cent possess two copies. When Kéri genotyped 200 adults who responded to ads seeking creative and accomplished volunteers he found that people with two copies of the neuregulin 1 mutation—about 12 per cent of the study participants—tended to score notably higher on measures of creativity, compared with other volunteers with one or no copy of the mutation. Those with one copy were also judged to be more creative, on average, than volunteers without the mutation. All told, the mutation explained between three and eight per cent of the differences in creativity, Kéri says, speculating that the mutation dampens the prefrontal cortex of the brain, which reins in mood and behaviour. This change could unleash creative potential in some people and psychotic delusions in others.