Can't carry a tune? Chances are you can blame your parents. By studying twins' ability to perceive sour notes in familiar tunes, a team has concluded that the perception of relative pitch is highly heritable.
Using the so-called Distorted Tunes Test, a team led by geneticist Dennis Drayna of the National Institute on Deafness and Other Communication Disorders in Bethesda, Maryland, tested pitch perception in 284 pairs of female twins from the Adult Twin Registry at St. Thomas' Hospital in London, United Kingdom. The twins ranged in age from 18 to 74, and about half the pairs were identical. The Distorted Tunes Test involves short snatches of 26 familiar melodies, such as "Silent Night," most of them with one or more notes altered. Subjects indicate whether the tune sounds right; anyone who gets more than three tunes wrong is judged to be somewhat tune deaf.
The scores of the identical twins correlated far better than those of the fraternal twins, showing the trait is strongly influenced by genes, the team reports in the 9 March issue of Science. Indeed, the researchers estimated the heritability for tune deafness at 0.80; about as high as it gets for genetically complex traits, and rivaling features such as height.
The study is "important" and clearly demonstrates a biological basis for pitch discrimination, says Evan Balaban of The Neurosciences Institute in San Diego. But he's reluctant to buy the heritability estimate, in part because twins are somewhat more prone than other children to developmental disabilities. Pairs of twins who are tune deaf because of developmental problems might artificially inflate the heritability. Balaban points out that almost 40% of the twins showed some evidence of deficits in pitch recognition, compared with only 27% in the control group.