Genetic Basis of Traits

It is no longer controversial that genetic differences account for individual differences in all human traits, such as personality traits: About 40–50% of variations are attributable to genetic sources. Heritability estimates are even larger for more accurate measures of personality characteristics. The combined consideration of molecular genetic study results and findings from different genetically informative family studies yields that the genetic basis of personality traits reflects many gene variants of small effects, which interact in complex ways among each other and with environmental factors. Moreover, individual differences in the genetic makeup drive individual differences in experiences and thus influence the course of individual trait development within the opportunities provided by the environment.