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A Gene-Environment Interaction in Antisocial Behavior?

Comment on "Role of Genotype in the Cycle of Violence
in Maltreated Children" (Science, 2 August 2002)

David C. Rowe and Judith Rich Harris

Maltreatment of children is rightly condemned as brutal and harmful. However, the study by Caspi et al. [1] of the MAOA gene does not prove a causal connection between abuse in childhood and antisocial behavior in adulthood, because their research design for abuse was correlational.

As Caspi et al. reported, not all abused children become antisocial adults. Nor do all siblings become antisocial in a family in which abuse has occurred [2]. These findings suggest a possible role for other genes -- a gene x gene interaction, rather than the gene x environment interaction proposed by Caspi et al. The other gene or genes, present in the parents as well as the children (because children inherit their genes from their parents), might predispose the parents to behave abusively and, in conjunction with the low-MAOA allele, might increase the risk that the children will become antisocial.

Another possibility is that an environmental correlate of child abuse might be responsible for the interaction reported by Caspi et al. [3]. For example, abused children are often removed from their homes and are sometimes moved around repeatedly. The resulting disruption of their lives, rather than the abuse per se, could be the triggering environmental factor that predisposes children with the low-MAOA allele to become antisocial.

These observations are meant to clarify, rather than detract from, the pioneering contribution of Caspi et al. Their use of measured genotypes will make hypotheses testable that were previously not even on the table.

David C. Rowe
Division of Family Studies and Human Development &
Graduate Interdisciplinary Program in Genetics
University of Arizona

Judith Rich Harris
Middletown, New Jersey


1. Caspi, A., McClay, J., Moffitt, T. E., Mill, J., Martin, J., Craig, I. W., Taylor, A., & Poulton, R. (2002, August 2). Role of genotype in the cycle of violence in maltreated children. Science, 297, 851-854.

2. Rowe, D. C. (1994). The limits of family influence. New York: Guilford.
Rowe, D. C. (2001). Biology and Crime. Los Angeles: Roxbury.

3. Harris, J. R. (1998). The Nurture Assumption. New York: Free Press.

Version 1.0
September 9, 2002

Citation (American Psychological Association format):
Rowe, D. C., & Harris, J. R. (2002, September 9). A gene-environment interaction in antisocial behavior? Retrieved [insert date] from the World Wide Web:

Copyright Notice
Copyright 2002 by David C. Rowe & Judith Rich Harris.
Permission is granted to link to this essay and to quote from it briefly. All other rights reserved.
For permission to reprint, contact Charles S. Harris, .

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