Why Is an Early Start of Training Related to Musical Skills in Adulthood? A Genetically Informative Study

310 professional musicians plus 7,786 Swedish twins

Swedish adults - a professional-musician sample and a population twin sample from the Swedish Twin Registry

The only genetically informative test of the "start music early" claim, which is the most common piece of practical advice in music education and rests almost entirely on cross-sectional comparisons of early- and late-trained musicians. The design separates three explanations for why early starters end up better: more accumulated practice, a genuine sensitive period, and familial factors that cause both the early start and the later skill.

Earlier onset of training was associated with higher musical aptitude and higher musical achievement. After adjusting for LIFETIME PRACTICE HOURS, onset still predicted aptitude (p < .001) but no longer predicted achievement (p > .14) - so most of the early-start advantage in achievement is simply accumulated hours. The remaining aptitude association was fully explained by FAMILIAL factors in the genetically informative analysis. Age of onset is itself substantially heritable, with reported variance components of roughly 39% genetic, 10% shared environment and 51% unique environment (these interval estimates come from a secondary summary and should be verified before being relied on). Authors' conclusion: "these findings provide little support for a sensitive period for music but highlight that familiar factors play an important role for associations between age of onset of training and skills in adulthood."

Directly targeted. The paper's finding is that the confound explains the phenomenon: children who start early are children from families that produce musical skill, and once that is modelled the sensitive-period signal disappears.

Unreplicated. It is consistent with Mosing et al. (2014) from the same group and with Wesseldijk, Gordon, Mosing and Ullén (2023), whose co-twin control found no causal effect of early music training on verbal ability at 18. It sits against a large cross-sectional neuroimaging literature reporting early-onset advantages, none of which is genetically informative.