Molecular genetic research on personality

This chapter provides an overview of molecular genetic research on personality, which aims to link variation in DNA to individual differences in personality. The landscape of this research has changed dramatically over the last decades. The field has moved from candidate gene investigations with single genetic variants studied in just a few hundred participants and slightly larger but still underpowered, genome-wide linkage studies to very large meta-analyses of genome-wide association studies, in which millions of genetic variants across the entire human genome are investigated in half a million people. Together, these studies have shown that a very large number of specific genetic variants, each with a very small effect size, are likely implicated in explaining human variation in personality. The large sets of genes for personality have a variety of functions in the brain and other parts of the body, and partly overlap with psychiatric and health-related phenotypes. Yet, the exact biological mechanisms of this polygenic variation and the causal mechanisms among genes, personality, and related phenotypes largely remain to be understood. It is expected that soon novel molecular genetic/omics approaches will be applied to personality. In addition, innovative longitudinal approaches on how the identified genes or gene sets are implicated in the development of individual differences in personality, while considering environmental influences, continue to be needed. Ultimately, this should yield novel insights into how genes relate to personality development and how this affects important life outcomes such as health and well-being.