Kids becoming less alike: A behavioral genetic analysis of developmental increases in personality variance from childhood to adolescence

Kids becoming less alike: A behavioral genetic analysis of developmental increases in personality variance from childhood to adolescence. René Mõttus et al. Journal of Personality and Social Psychology , February 2018. https://www.researchgate.net/publication/323112699_Kids_becoming_less_alike_A_behavioral_genetic_analysis_of_developmental_increases_in_personality_variance_from_childhood_to_adolescence

Lay summary: Children and adolescents tend to grow less alike in personality. It is largely their genetic differences that make them increasingly different. This may be because genetic influences predispose children to particular experiences that then amplify these influences.

Abstract: Recent work in personality development has indicated that the magnitude of individual differences in personality increases over child development. Do such patterns reflect the differentiation of individuals by genotype, an increasing influence of environmental factors, or some (interactive) combination of the two? Using a population-based sample of over 2,500 twins and multiples from the Texas Twin Project, we estimated age trends in the variances in self- and parent-reported measures of the Big Five personality traits between ages eight and eighteen years. We then estimated age trends in the genetic and environmental components of variance in each measure. Individual differences in personality increased in magnitude from childhood through mid-adolescence. This pattern emerged using both children's self-reports and ratings provided by their parents, and was primarily attributable to increases in the magnitude of genetic influences. Most of the increasing genetic variance appeared non-additive, pointing to the possibility that developmental processes tend to make genetically similar individuals disproportionately more alike in their personality traits over time. These findings could reflect increasing or accumulating effects of trait-by-trait interactions; person-by-environment transactions whereby genetically similar people are disproportionally likely to experience similar environments; the activation of dominant genes across developmental transitions (e.g., puberty); or some combination of these three processes, among other factors. Theories of personality development will need to accommodate these descriptive findings, and longitudinal, genetically informed designs are needed to test some of the specific hypotheses springing from this study.

Keywords: Development; Personality; Variance; Behavioral Genetics; Non-additive