Heredity, Environment, and Personality Change: Evidence From the Texas Adoption Project


  • The research reported in this article was supported by Grants MH-24280 from the National Institute of Mental Health and BNS-7902918 and BNS-8209882 from the National Science Foundation We are grateful to Robert Plomin and three anonymous reviewers for their comments on the manuscript

concerning this article should be addressed to John C Loehlin, Department of Psychology, University of Texas, Austin, TX 78712


ABSTRACT Personality changes over time can be analyzed by the same twin and adoption methods used to analyze the genetic and environmental influences on a trait at a given time Composite parent rating measures of Extraversion, Socialization, and Stability made on two occasions approximately 10 years apart on 229 adopted and 83 nonadopted children from the Texas Adoption Project were used to illustrate this point in two ways The first was based on correlations among family members, from which it appeared that by far the chief source of individual change was neither the genes nor shared family environment, but individual experience (and/or measurement error) The second was via a path-analytic approach to changes in the means of adopted and natural children, from which it appeared that, nonetheless, the children were tending to change on the average in the direction of their genetic parents' personalities