Human behavioral genetic research aimed at characterizing the existence and nature of genetic and environmental influences on individual differences in cognitive ability, personality and interests, and psychopathology is reviewed. | Annu. Rev. Neurosci. 1998. 21:1–24 Copyright c 1998 by Annual Reviews Inc. All rights reserved GENETIC AND ENVIRONMENTAL INFLUENCES ON HUMAN BEHAVIORAL DIFFERENCES Matt McGue and Thomas J. Bouchard, Jr Department of Psychology and Institute of Human Genetics, 75 East River Road, University of Minnesota, Minneapolis, Minnesota 55455; e-mail: Mmcgue@ KEY WORDS: heritability, gene-environment interaction and correlation, nonshared environment, psychiatric genetics ABSTRACT Human behavioral genetic research aimed at characterizing the existence and nature of genetic and environmental influences on individual differences in cognitive ability, personality and interests, and psychopathology is reviewed. Twin and adoption studies indicate that most behavioral characteristics are heritable. Nonetheless, efforts to identify the genes influencing behavior have produced a limited number of confirmed linkages or associations. Behavioral genetic research also documents the importance of environmental factors, but contrary to the expectations of many behavioral scientists, the relevant environmental factors appear to be those that are not shared by reared together relatives. The observation of genotype-environment correlational processes and the hypothesized existence of genotype-environment interaction effects serve to distinguish behavioral traits from the medical and physiological phenotypes studied by human geneticists. Behavioral genetic research supports the heritability, not the genetic determination, of behavior. INTRODUCTION One of the longest, and at times most contentious, debates in Western intellectual history concerns the relative influence of genetic and environmental factors on human behavioral differences, the so-called nature-nurture debate (Degler 1991). Remarkably, the past generation of behavioral genetic research has led 1 0147-006X/98/0301-0001$ 2 McGUE & BOUCHARD many to conclude that it may now be time to retire this debate in favor of
