Personality and Temperament

Abstract Temperament is an early developing set of characteristics related to later personality. Commonly studied dimensions of temperament include activity level, anger/frustration, behavioural inhibition/fear, effortful control and positive affect. Personality includes a range of traits, including major traits of extraversion, neuroticism and impulsivity/sensation‐seeking. Different aspects of personality and temperament are related to important developmental outcomes such as behavioural problems and psychopathology. Both behavioural genetic and molecular genetic research have contributed to the understanding of major traits of temperament and personality. Behavioural genetic approaches use twin and adoption study designs to estimate genetic and environmental contributions to individual differences in traits. Most behavioural genetic studies have found substantial heritability for personality and temperament. Molecular genetic investigations focus on the effects of specific genes (primarily dopamine‐ and serotonin‐related genes in studies of temperament and personality). Key Concepts: Rothbart's broad extraversion/surgency, negative affectivity and effortful control dimensions of temperament are related to three of the Big Five personality factors: extraversion, neuroticism and conscientiousness, respectively. The results of twin and adoption studies have shown significant genetic and nonshared environmental variance in temperament and personality. Contemporary researchers investigating personality and temperament from a molecular genetic standpoint typically use either candidate gene studies or genome‐wide association studies (GWAS). Although behavioural and molecular genetics are separate fields, most behavioural genetic researchers have begun incorporating molecular techniques into their research programs. Genotype–environment interactions, genotype–environment correlations and endophenotype approaches are utilised in genetic studies of temperament and personality. Candidate gene studies of dopaminergic and serotonergic genes have informed ongoing molecular genetic research in temperament and personality. Increasingly, studies of other candidate genes as well as GWAS approaches are also extant in the literature.