Behavior Genetics

, Volume 19, Issue 4, pp 605–608

Of biases and more in the study of twins reared together: A reply to grayson

  • John K. Hewitt


Grayson (see the preceding paper) discusses some circumstances in which estimates of genetic and environmental parameters derived from the study of twins reared together may be biased and documents in those circumstances what the magnitude of the biases may be. As Grayson suggests, the points he makes have been made previously by various authors and issues such as the power to detect dominance have been analyzed at some length. This paper draws attention to some other sources of variation which Grayson does not consider but which have been considered by other writers and which might have somewhat different consequences for the estimation of shared environmental effects. The classical twin study has never been an end in itself, but it is the nucleus of a systematic genetic approach to the study of human behavior.

Key Words

twins model fitting nonadditive effects family environment 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Eaves, L. J. (1970).Aspects of Human Psychogenetics, Unpublished Ph.D. thesis, University of Birmingham, Birmingham.Google Scholar
  2. Eaves, L. J. (1976). A model for sibling effects in man.Heredity,36:205–214.PubMedGoogle Scholar
  3. Eaves, L. J. (1977). Inferring the causes of human variation.J. Roy. Stat. Soc. 140:324–355.Google Scholar
  4. Eaves, L. J. (1978). Twins as a basis for the causal analysis of personality. In Nance, W. E. (ed.),Twin Research: Psychology and Methodology, Alan Liss, New York.Google Scholar
  5. Eaves, L. J. (1979). The use of twins in the analysis of assortative mating.Heredity 43:399–409.PubMedGoogle Scholar
  6. Eaves, L. J. (1988). Dominance alone is not enough.Behav. Genet. 18:27–33.PubMedGoogle Scholar
  7. Eaves, L. J., Last, K., Young, P. A., and Martin, N. G. (1978). Model fitting approaches to the analysis of human behaviour.Heredity 41:249–320.PubMedGoogle Scholar
  8. Fulker, D. W. (1979). Nature and nurture: Heredity. In Eysenck, H. J. (ed.),The Structure and Measurement of Intelligence, Springer-Verlag, Berlin.Google Scholar
  9. Grayson, D. A. (1989). Twins reared together: Minimizing shared environmental effects.Behav. Genet. 19:593–604.PubMedGoogle Scholar
  10. Heath, A. C. (1987). The analysis of marital interaction in cross-sectional twin data.Acta Med. Gemellol 31:41–49.Google Scholar
  11. Heath, A. C., and Eaves, L. J. (1985). Resolving the effects of phenotype and social background on mate selection.Behav. Genet. 15:15–30.PubMedGoogle Scholar
  12. Heath, A. C., Neale, M. C., Hewitt, J. K. Eaves, L. J., and Fulker, D. W. (1989). Testing structural equation models for twin data using LISREL.Behav. Genet. (in press).Google Scholar
  13. hewitt, J. K. (1984). Normal components of personality variation.J. Personal. Soc. Psychol. 47:671–675.Google Scholar
  14. Hewitt, J. K., Eaves, L. J., Neale, M. C., and Meyer, J. (1988). Resolving causes of longitudinal continuity or “tracking.” I. Longitudinal twin studies during growth.Behav. Genet. 18:133–152.PubMedGoogle Scholar
  15. Jinks, J. L., and Fulker, D. W. (1970). Comparison of the biometrical genetical, MAVA and classical approaches to the analysis of human behavior.Psychol. Bull. 73:311–349.PubMedGoogle Scholar
  16. Martin, N. G., Eaves, L. J., Kearsey, M. J., and Davies, P. (1978). The power of the classical twin study.Heredity 40:97–118.PubMedGoogle Scholar
  17. Martin, N. G., Eaves, L. J., Heath, A. C., Jardine, R., Feingold, L., and Eysenck, H. J. (1986). The transmission of social attitudes.Proc. Natl. Acad. Sci. 83:4363–4368.Google Scholar
  18. Neale, M. C., and Stevenson, J. (1989). Rater bias in the EASI temperament scales: A twin study.J. Personal Soc. Psychol. 56:446–455.Google Scholar

Copyright information

© Plenum Publishing Corporation 1989

Authors and Affiliations

  • John K. Hewitt
    • 1
  1. 1.Department of Human Genetics, Medical College of VirginiaVirginia Commonwealth UniversityRichmond

Personalised recommendations