In this study, using genetically informed longitudinal analysis, we sought to examine the genetic and environmental contributions to stability and change in conscientiousness, one of the big five personality traits. Although... [ view full abstract ]
In this study, using genetically informed longitudinal analysis, we sought to examine the genetic and environmental contributions to stability and change in conscientiousness, one of the big five personality traits. Although the stability was due to genetic influence according to accumulated evidence on heritability of various variables, the etiology of changes is more likely to be unclear. We then focused more on changes in conscientiousness to test whether the variance of changes was significant, and to what extent the variance of changes can be explained by the genetic or environmental factor. We used two-wave longitudinal data collected from Japanese adolescent twins whose ages ranged from 9 to 18. Data collections were one year apart. Completed online questionnaires were received from 2,022 twin pairs, comprising 708 mMZ, 671 fMZ, 111 mDZ, 110 fDZ, and 422 oDZ pairs at Wave 1, and from 1,285 twin pairs, comprising 436 mMZ, 445 fMZ, 71 mDZ, 62 fDZ, and 271 oDZ pairs at Wave 2. Conscientiousness was assessed by the following five scales: Conscientiousness items form Big Five Inventory-44, Chernyshenko conscientiousness scales, Effortful Control items from Adult Temperament Questionnaire, Self-control scale, and grit scale. At both time points, common pathway models fit best to the data, and there was a heritable general factor (h2 = 72.1%, 70.6%, respectively). Latent change analysis with longitudinal twin data revealed that cross-time stability was largely accounted for by genetic influence (66.1%), whereas change over time was by non-shared environmental influence (63.0%). Our results demonstrated that heritability for level was greater than heritability for change, while environmentability for change was greater than environmentability for level, suggesting that the stability of conscientiousness over time appears to be primarily a function of enduring genetic influences, and that non-shared environmental influence is primarily responsible for change in conscientiousness over time. In addition, there was a high non-shared environmental correlation between level and change (r = -.623), indicating that the non-shared environmental factor that affects the stability of trait conscientiousness influences change in opposite direction.
