The Genetics of Personality

Abstract

Theoretical, methodological and empirical advances have created a resurgence of interest in personality within the behavioral sciences. Theoreticians have made progress in explicating the nature of personality by identifying a reduced set of dimensions that capture much, albeit not all, of the between-individual variation in personality. Clinical researchers have documented the importance of this variation in predicting and understanding the etiology of mental illness and other important life outcomes and neurobiologists are beginning to identify the neural structures and processes that are the biological basis of personality. Twin and adoption research has consistently implicated the importance of genetic influences on individual differences in personality, suggesting that approximately 50% of the variance in personality characteristics is associated with inherited genetic factors, some of which may be nonadditive in effect. Remarkably, the environmental factors that account for the remaining 50% of the variance appear to be those that create differences rather than similarities among reared-together relatives. The substantial heritability of personality characteristics has provided justification for investigations aimed at identifying the specific genes that underlie individual differences in personality. Despite considerable effort, candidate genes studies have yielded only a few promising leads over the past 20 years. More recently, genome-wide association studies have similarly failed to yield any confirmed associations of specific genetic variants with personality, in all likelihood, because the effect associated with any single genetic variant is very small and so will require massive sample sizes to detect. One promising area of personality research that sets this phenotype apart from most that are studied by geneticists involves characterizing the complex interplay between genetic and environmental factors in the development of personality.