Genetics of Human Character and Temperament

Abstract

Abstract Personality is the way individuals learn to shape and adapt to changing conditions. The character domain of personality is what people make of themselves intentionally, whereas temperament involves automatic emotional reactivity. Prior studies assuming genes act independently failed to identify most personality‐related genes. Therefore, we used machine learning to identify naturally occurring clusters of genes. In independent genome‐wide association studies from different cultures, we found many replicable multigene clusters among 972 genes that accounted for nearly all the heritability expected from twin studies. Temperament depended on multigene clusters in molecular systems for associative conditioning of habits and emotional reactivity. Character depended on clusters in intentional networks: self‐control of goals via Inositol–Calcium signalling, and self‐awareness of values via long‐non‐coding RNAs unique to modern humans. These three systems of learning and memory allow the integration of habits, goals, and values via the regulation of gene expression to maintain healthy functioning despite variable environmental conditions. Key Concepts The ‘Hidden Heritability Problem’ with complex phenotypes. Human personality is moderately heritable (∼50%) according to many twin and adoption studies, but few of the specific genes for personality were recognised by studies that assumed the genes involved were acting independently. Human character and temperament have a complex architecture: the same gene or cluster of genes can be associated with multiple phenotypes, and different genes or clusters of genes can have the same phenotype. Empirical methods of pattern recognition based on machine learning allow efficient and replicable deconstruction of the complex architecture of human personality. Human personality is a complex phenotype with multiple components. The temperament domain of personality is the disposition of a person to learn how to behave, react emotionally and form attachments automatically by associative conditioning of their habits. Human character is the self‐regulatory domain of personality – that is, the way a person shapes and adapts their goals and values to ever‐changing external and internal conditions. Human character and temperament are each comprised of multiple components that depend on how people function in different situations and environments. Character and Temperament involve adaptive processes of learning, not fixed traits. Human personality is the integrated expression of three genotypic systems that regulate learning and memory by associative conditioning, intentional self‐control and creative self‐awareness. Most of the genes for personality are unique to a single learning system, but there is sufficient overlap to permit integrated functioning. The integration of human character and temperament allows flexible regulation of gene expression to maintain healthy functioning despite variable environments.