The genetic basis of personality at different ages: a cross-sectional twin study

The hypothesis that the stability of personality in adults is owing to genetic factors was examined by fitting genetic path models in a sample of young adult twins (122 monozygotic and 121 dizygotic pairs aged 18–25 yr) and a sample of older adult twins (145 monozygotic and 136 dizygotic pairs aged 30–65 yr). The significance of genetic factors in personality, as measured by the Dimensional Assessment of Personality Pathology (DAPP) at these two ages was tested. It was found that models that specified no genetic factors did not fit the data on 15 of 18 DAPP dimensions in the older adult twins, in contrast to only seven dimensions in the younger adult twins. These results suggest that role of genetic factors is more significant in later as opposed to early adulthood and may account for the greater stability of personality observed during the course of adult life.