Physical activity and personality: A behaviour genetic analysis

ObjectivesThe aim of this study was to obtain a heritability estimate of exercise behaviour in twins and to examine the genetic and environmental contributions to phenotypic associations between personality and exercise behaviour.DesignTwin study was used, the sample including 339 twin pairs (105 MZ and 234 DZ), between 15 and 22 years of age (M = 18.6, SD = 2.31).MethodThe participants filled in a NEO-FFI personality inventory and answered two questions about the frequency (FPE) and intensity (IPE) of physical exercise. We also calculated the composite physical exercise score (CS) representing a combination of FPE and IPE items.ResultsThe broad heritability estimates of three physical exercise variables (FPE, IPE, CS) were significant, with results in the 0.55 to 0.69 range. We found significant phenotypic associations with neuroticism and extraversion. Contrary to our expectations, correlations with conscientiousness were not significant. People scoring higher on extraversion and lower on neuroticism reported exercising more often and more intensely. Phenotypic association between personality traits and physical exercise variables were due to overlapping genetic influences.ConclusionsOur results indicate that the genetic factors contributing to an active lifestyle overlap with those contributing to personality traits extraversion and neuroticism, in line with the “nature” hypothesis which infers the presence of biological differences in predisposition for regular physical activity.