TO MASTER the violin takes 10,000 hours of practice. Put in that time and expertise will follow. This, at least, is what many music teachers—following Malcolm Gladwell’s prescription for achieving expertise in almost any field by applying the requisite amount of effort—tell their pupils. Psychologists are more sceptical. Some agree practice truly is the thing that separates experts from novices, but others suspect genes play a role, too, and that without the right genetic make-up even 20,000 hours of practice would be pointless.

A study just published in Psychological Science, by Miriam Mosing of the Karolinska Institute, in Sweden, suggests that the sceptics are right. Practising music without the right genes to back that practice up is indeed useless.

Dr Mosing drew her conclusion in a time-honoured way—by studying twins. She and her colleagues surveyed 1,211 pairs of identical twins (who share all their genes) and 1,358 pairs of fraternal twins (who share half) born between 1959 and 1985. They asked each participant whether he or she played a musical instrument or actively engaged in singing. Those who did were asked to estimate how many hours a week they had practised at different ages. From this Dr Mosing was able to calculate a score for each individual’s lifetime practice. Anyone who did not play an instrument or sing got a score of zero.

Next, Dr Mosing tested her volunteers’ musical abilities. Doing this by conducting recitals would be impossible. It would be hard enough to quantify the relative merits of people playing the same instrument, let alone to compare the skills of, say, drummers with those of saxophonists or singers. Instead, she used three proxy tests.

The first measured a person’s ability to detect differences in pitch. Each participant heard two notes. Sometimes the second was different from the first. Sometimes it was not. Participants had to say whether the second was higher or lower than the first, or the same.

The next test, of appreciation of melody, asked people to distinguish between two sequences of four to nine notes, in which one sequence would sometimes differ from the other in the pitch of a single note. The final test, of sensitivity to rhythm, required volunteers to decide whether two sequences of five to seven notes with the same pitch, but possibly different time intervals, were indeed the same or different.

Expert musicians are exceptionally good at detecting differences in pitch, melody and rhythm in these sorts of tests. Dr Mosing therefore expected to find that if someone had put in sufficient practice time his musical ability would be as high as an expert’s. But that was not true. In fact, there appeared to be no relationship between practice and musical ability of the sort she was measuring. A twin who practised more than his genetically identical co-twin did not appear to have better musical abilities as a result. In one case the difference between two such twins was 20,228 hours of practice, even though the pair’s measured musical abilities were found to be the same.

That is not to say practice has no value. Playing an instrument and singing are physical skills, and do take a long time to master. But, though the experiment could not measure this directly, it is a fair bet that only those with high musical ability in the first place can ever hope to master these skills—and Dr Mosing has shown that musical ability has a big genetic component.

One other curious fact to emerge from the study was that the practice of practice itself seems to be under genetic control. Even allowing for counter-examples such as the identical twins with a 20,000 hour difference in their lifetime practice regimes, such twins are more similar in their attitudes to practising than are fraternal ones. For children who find practising the violin a chore, this may be the study’s most useful result. When asked by their teachers why they have not practised during the previous week, they can now blame their genes.