Behavior Genetics

, Volume 30, Issue 6, pp 487–495

Parental Education and Child's Verbal IQ in Adoptive and Biological Families in the National Longitudinal Study of Adolescent Health

  • Michelle Neiss
  • David C. Rowe


This study compared adoptive children and matched, biological children to estimate the genetic and environmental effect of years of mothers' and fathers' education on children's verbal intelligence (VIQ), as assessed by knowledge of vocabulary words. Adoptive and biological adolescent children in the National Longitudinal Study of Adolescent Health (Add Health) were matched for sex, age, parental education, and ethnicity. The adolescents all resided with two parents. Structural equation modeling was employed using Mx to estimate the genetic and transmissible environmental components of the correlation between parental education and children's VIQ. The mother-child and father-child correlations in biological families were .41 and .36, respectively, vs .16 and .18 in adoptive families. As suggested by these correlations, both genetic and shared environmental influences were statistically significant in the Mx models. We conclude that parental education exerts a modest shared environmental effect, explaining no more than 3 to 4% of the variation in verbal intelligence.

Adoption study verbal IQ heritability shared environment 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Bergeman, C. S., Plomin, R., DeFries, J. C., and Fulker, D. W. (1988). Path analysis of general and specific cognitive abilities in the Colorado Adoption Project: Early childhood. Person.Indiv.Diff. 9:391–395.Google Scholar
  2. Boomsma, D. I., van Baal, G., and Caroline, M. (1998). Genetic influences on childhood IQ in 5-and 7-year-old Dutch twins. Dev.Neuropsychol. 14:115–126.Google Scholar
  3. Bouchard, T. J., Jr., Lykken, D. T., McGue, M., Segal, N. L., and Tellegen, A. (1990). Sources of human psychological differences: The Minnesota study of twins reared apart. Science 250:223–250.Google Scholar
  4. Caroll, R. B. (1993). Human Cognitive Abilities: A Survey of Factor-Analytic Studies, Cambridge University Press, New York.Google Scholar
  5. Chipuer, H. M., Rovine, M. J., and Plomin, R. (1990). LISREL modeling: Genetic and environmental influences on IQ revisited. Intelligence 14:11–29.Google Scholar
  6. Fulker, D. W. (1988). Genetic and cultural transmission in human behavior. In Weir, B. S., Goodman, M., Eisen, E. J., and Namkoong, G. (eds.), Proceedings of the Second International Conference on Quantitative Genetics, Sinauer Associates, Sunderland, MA, pp. 318–340.Google Scholar
  7. Loehlin, J. C., Horn, J. M., and Willerman, L. (1989). Modeling IQ change: Evidence from the Texas Adoption Project. Child Dev. 60:993–1004.Google Scholar
  8. Martin, N. G., Eaves, L. J., Kearsey, M. J., and Davies, P. (1978). The power of the classical twin study. Heredity 40:97–116.Google Scholar
  9. Neale, M. C., and Cardon, L. R. (1992). Methodology for Genetic Studies of Twins and Families, Kluwer Academic, Dordrecht.Google Scholar
  10. Pal, S., Shyam, R., and Singh, R. (1997). Genetic analysis of general intelligence 'g': A twin study. Person.Indiv.Diff. 22: 779–780.Google Scholar
  11. Plomin, R., and Petrill, S. A. (1997). Genetics and intelligence: What's new? Intelligence 24:53–77.Google Scholar
  12. Plomin, R., Fulker, D. W., Corley, R., and Defries, J. C. (1997). Nature, nurture, and cognitive development from 1 to 16 years: A parent-offspring adoption study. Psychol.Sci. 8:442–447.Google Scholar
  13. Rowe, D. C. (1994). The Limits of Family Influence: Gene, Experience, and Behavior, Guilford, New York. Rowe, D. C.Google Scholar
  14. Jacobson, K. C., and Van den Oord, E. J. C. G. (1999a). Genetic and environmental influences on vocabulary IQ: Parental education level as moderator. Child Dev. 70:1151–1162.Google Scholar
  15. Rowe, D. C., Vesterdal, W. J., and Rodgers, J. L. (1999b). Herrnstein's syllogism: Genetic and shared environmental influences on IQ, education, and income. Intelligence 26:405–423.Google Scholar
  16. Scarr, S., and Weinberg, R. A. (1978). The influence of “family background” on intellectual attainment. Am.Sociol.Rev. 43:674–692.Google Scholar
  17. Scarr, S., and Weinberg, R. A. (1983). The Minnesota adoption studies: Genetic differences and malleability. Child Dev. 54: 260–267.Google Scholar
  18. Scarr, S., Weinberg, R. A., and Waldman, I. D. (1993). IQ correlations in transracial adoptive families. Intelligence 17: 541–555.Google Scholar
  19. Stoolmiller, M. (1998). Correcting estimates of shared environmental variance for range restriction in adoption studies using a truncated multivariate normal model. Behav.Genet. 28: 429–441.Google Scholar
  20. Treva, R., Fulker, D. W., and DeFries, J. C. (1986). Multivariate path analysis of specific cognitive abilities in the Colorado Adoption Project. Behav.Genet. 16:107–125.Google Scholar

Copyright information

© Plenum Publishing Corporation 2000

Authors and Affiliations

  • Michelle Neiss
    • 1
  • David C. Rowe
    • 1
  1. 1.Division of Family Studies and Human DevelopmentUniversity of ArizonaTucson

Personalised recommendations