Genetic and Environmental Effects on Openness to Experience, Agreeableness, and Conscientiousness: An Adoption/Twin Study


  • The Swedish Adoption/Twin Study of Aging is an ongoing study conducted at the Department of Environmental Hygiene of the Karolinska Institute in Stockholm in collaboration with the Research Center for Developmental and Health Genetics at Pennsylvania State University. The research reported herein was supported in part by a grant from the National Institute of Aging (AG-04563) and by the Successful Aging Program of the John D. and Catherine T. MacArthur Foundation. C. S. Bergeman was supported by a Public Health Service Interdisciplinary Training Fellowship in Gerontology (T32 AG00048–12). Preliminary analyses of these data have been cited in Plomin and McClearn (1990); Plomin, Chipuer, and Loehlin (1990); and Rose, Kaprio, Williams, Viken, and Obremski (1990).

Address correspondence to C. S. Bergeman, Department of Psychology, University of Notre Dame, 118 Haggar Hall, Notre Dame, IN 46556.


ABSTRACT Previous research has indicated that extraversion and neuroticism are substantially affected both by genotype and environment. This study assesses genetic and environmental influences on the other three components of the five-factor model of personality: Openness to Experience, Agreeableness, and Conscientiousness. An abbreviated version of the NEO Personality Inventory (NEO-PI) was administered to 82 pairs of identical twins and 171 pairs of fraternal twins reared apart and 132 pairs of identical twins and 167 pairs of fraternal twins reared together. Estimates of genetic and environmental effects for Openness and Conscientiousness were similar to those found in other studies of personality: Genetic influence was substantial and there was little evidence of shared rearing environment. Results for Agreeableness were different: Genetic influence accounted for only 12% of the variance and shared rearing environment accounted for 21% of the variance. Few significant gender or age differences for genetic and environmental parameters were found in model-fitting analyses.