Music and verbal ability - a twin study of genetic and environmental associations.

Musical aptitude and music training are associated with language-related cognitive outcomes, even when controlling for general intelligence. However, genetic and environmental influences on these associations have not been studied, and it remains unclear whether music training can causally increase verbal ability. In a sample of 1,336 male twins, we tested the associations between verbal ability measured at time of conscription at age 18 and two music related variables: overall musical aptitude and total amount of music training before the age of 18. We estimated the amount of specific genetic and environmental influences on the association between verbal ability and musical aptitude, over and above the factors shared with general intelligence, using classical twin modelling. Further, we tested whether music training could causally influence verbal ability using a co-twin-control analysis. Musical aptitude and music training were significantly associated with verbal ability. Controlling for general intelligence only slightly attenuated the correlations. The partial association between musical aptitude and verbal ability, corrected for general intelligence, was mostly explained by shared genetic factors (50%) and non-shared environmental influences (35%). The co-twin-control-analysis gave no support for causal effects of early music training on verbal ability at age 18. Overall, our findings in a sizeable population sample converge with known associations between the music and language domains, while results from twin modelling suggested that this reflected a shared underlying aetiology rather than causal transfer.