Genetic and Rearing Environmental Influences on Adult Personality: An Analysis of Adopted Twins Reared Apart


  • This research has been supported by grants from the Pioneer Fund, the Seaver Institute, the University of Minnesota Graduate School, the Koch Charitable Foundation, the Spencer Foundation, the National Science Foundation (BNS-7926654), and the Harcourt Brace Jovanovich Publishing Co We would like to thank the following people for the time and effort they have given to testing the twins Margaret Keyes, Jeff McHenry, Elizabeth Rengel, Susan Resnick, Joy Fisher, Jan Englander, Ann Riggs, Kimerly J Wilcox, Mary Moster, Dan Moloney, and Ellen Rubin We are indebted to our colleagues and collaborators on the Minnesota Study of Twins Reared Apart project, Auke Tellegen, David Lykken, Bike Eckert, Leonard Heston, and Nancy L Segal for their help and advice We would also like to thank the Minneapolis Memorial Blood Bank, Herbert Polesky, Director, for the blood testing

Requests for reprints should be sent to Thomas J Bouchard, Jr, Department of Psychology, Elliott Hall, University of Minnesota, 75 East River Road, Minneapolis, MN 55455


ABSTRACT We report a genetic and environmental analysis of California Psychological Inventory (CPI) scale scores gathered on a sample of 45 sets of monozygotic twins reared apart (MZA) and 26 sets of dizygotic twins reared apart (DZA) Analysis of twin intraclass correlations and the results of models fit to the twin data demonstrate that the heritability of most scales and five factors of the CPI is about 50 When compared to results from studies of adult MZ and DZ twins reared together few of the scales demonstrate any common family environmental influence Placement coefficients on the Family Environment Scale (FES) can explain only a minor portion of the correlations for twins reared apart The influence of specific rearing environmental factors on adult personality was evaluated by analyzing the relationship between the FES and the CPI in this adoptee sample One FES factor (Cohesion vs Conflict) does correlate substantially with the CPI factor of Consensuality and may account for up to 24% of the variance in that factor, but the retrospectively gathered