Last year, Simiak Baharloo and colleagues showed that absolute pitch — the ability to identify precisely and rapidly the pitch of a note — has a substantial genetic component (see Highlights, October 2000). Now, Dennis Drayna and colleagues focus on relative pitch (RP) — the ability to perceive pitch alterations — and find that it also has a surprisingly large genetic component.

To investigate the relative contributions of genetics and the environment to RP perception, Drayna et al. used a twin study and a modernized distorted tunes test (DTT), which aims to minimize the effects of cultural bias and musical training. They tested 136 monozygotic (MZ) and 148 dizygotic (DZ) Caucasian female twins for their ability to spot false notes in popular tunes. Statistical analysis of the results revealed a significant difference in the DTT scores between MZ and DZ twins, which indicates a strong genetic component to RP perception. Additionally, Drayna et al. showed that RP perception is largely independent of age and peripheral hearing — the ability to hear sounds. This last finding indicates that RP and peripheral hearing might involve separate parts of the auditory system.

The correlation of DTT scores for the MZ data set was calculated at 0.67 compared with 0.44 for the DZ data set. Sophisticated statistical data modelling indicated a strong influence of additive genetic factors and a small environmental contribution, for example from musical training. The same models establish heritability, which is the proportion of variance attributable to genetic differences, at 0.71–0.80 — a very high score for a complex genetic trait. But the authors point out that the results will need to be replicated in other populations.

By showing that RP perception might be partly 'hardwired', this study has struck a chord among cognitive scientists who are studying communication disorders, and who noticed a long time ago that musicality and language ability go together. They might now be encouraged to look for the genetic basis of such disorders.