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Quantitative genetic analysis of Internalising and Externalising Problems in a large sample of 3-year-old twins

Published online by Cambridge University Press:  21 February 2012

JC van der Valk ,
FC Verhulst ,
TM Stroet  and
DI Boomsma
JC van der Valk*
Affiliation:
Department of Child and Adolescent Psychiatry, Sophia Children's Hospital, Rotterdam, The Netherlands; Department of Psychonomics, Free University, Amsterdam, The Netherlands. [email protected]
FC Verhulst
Affiliation:
Department of Child and Adolescent Psychiatry, Sophia Children's Hospital, Rotterdam, The Netherlands.
TM Stroet
Affiliation:
Department of Psychonomics, Free University, Amsterdam, The Netherlands.
DI Boomsma
Affiliation:
Department of Psychonomics, Free University, Amsterdam, The Netherlands.
*
*Correspondence: JC van der Valk MA, Department of Child and Adolescent Psychiatry, Sophia Children's Hospital, Rotterdam, The Netherlands. Tel: 31 104636092; Fax: 31 104636803

Abstract

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For a quantitative genetic study of pre-school problem behaviours, we have collected data with the Child Behavior Checklist for 2 and 3-year-old children (CBCL 2/3). Questionnaires were completed by mothers of 3620 twin pairs: 633 monozygotic males, 581 dizygotic males, 695 monozygotic females, 519 dizygotic females and 1192 dizygotic opposite sex twin pairs. The genetic and environmental influences on the Externalising and Internalising Problem scales were estimated, simultaneously with sex differences and sibling interaction effects. Genetic factors explained most of the observed variance for both Externalising and Internalising Problems. Cooperative sibling interactions were found for Externalising Problems, indicating that twins reinforce each other's behaviour. Sex differences in genetic architecture were found for Externalising Problems. Genetic factors explained 75% of the variance in girls and 50% in boys. Shared environmental influences were only of importance in boys. For both problem scales, non-shared environmental factors accounted for 25 to 32% of the variance. The observed variances of Internalising Problems could be adequately explained by genetic and nonshared environmental factors, with genetic factors accounting for 68% of the variance.

Keywords

pre-school childrenproblem behaviourChild Behavior Checklisttwinsbehaviour genetics
Type
Articles
Information
Twin Research and Human Genetics , Volume 1 , Issue 1 , 01 February 1998 , pp. 25 - 33
Copyright
Copyright © Cambridge University Press 1998