WHEN IT COMES TO CRIME - HOW MUCH DO PARENTS MATTER?

In 1990, two researchers - Michael Gottfredson and Travis Hirschi -proposed a "general theory of crime" that is now widely accepted. According to this theory, low self- control is the primary cause of crime and related behaviors. Moreover, the theory states, adults' levels of self-control depend on the quality of parenting they received in early childhood.

Sociological studies offer evidence seeming to support both parts of this theory, solidifying its popularity. But John Paul Wright and Kevin Beaver argue that while low self-control indeed plays a key role in criminality, studies that blame parents for this trait in their children are fatally flawed because they are poorly designed and fail to consider the effects of genes.

Gottfredson and Hirschi claimed that "the magnitude of the 'genetic effect' is near zero," but Wright and Beaver counter that "a large body of literature. has arrived at a very different conclusion." Research, they say, shows that impulsivity and attention deficit hyperactivity disorder-both of which are aspects of low self-control-are highly heritable. For example, they note, one study by Spencer et al. found that "the mean heritability of ADHD. is approximately 0.75, which means that about 75% of the etiological contribution to this disorder is genetic."

This raises an obvious question: why do sociological studies consistently support the "bad parenting" theory? To find out, Wright and Beaver used data from 1,000 children participating in a Department of Education study. The information allowed the researchers to determine the children's levels of self- control, as well as their parents' styles of childrearing. Because 310 of the children were identical or fraternal twins, the researchers could also analyze gene effects (since identical twins share all of their genes, and fraternal twins share half).

First, Wright and Beaver analyzed their data using techniques common to sociological studies and ignoring genetic effects. Their findings consistently revealed a significant effect for several aspects of parenting.

Next, the researchers factored in the role of genes, also using what they say is a more rigorous study design. When they re-analyzed the data, they found that "parenting measures have a weak and inconsistent effect" on children's self-control. In fact, when the researchers used data solely from teachers' measurements of children's self-control, the effects of parenting nearly disappeared.

Wright and Beaver say this doesn't mean that parents don't matter. Instead, they say, "Parents likely influence their children in ways that are more complicated than is typically assumed. Parents may moderate the influence of specific child traits, or the traits of parents may interact in unique ways with the traits of each of their children." They note, too, that the genetically determined traits of a child are likely to influence how a parent treats the child.

The researchers conclude that "for self- control theory to be a valid theory of crime it must incorporate a more sophisticated understanding of the origins of self- control."

Editor's note: In a separate study involving the same 310 twins as the first study, Wright and Beaver analyzed the relationship between self-control and birth complications. They found that anoxia (oxygen deprivation) plays a strong role in impaired self-regulation in children. In contrast, they say, the effects of parental involvement (the only aspect of parenting linked to self- control in the second study) were "marginal in magnitude."

"Do parents matter in creating self-control in their children? A genetically informed test of Gottfredson and Hirschi's theory of low self-control," John Paul Wright and Kevin M. Beaver, Criminology, Vol. 43, No. 4, 2005, 1169-1202; and "Evaluating the effects of birth complications on low self- control in a sample of twins," Kevin M. Beaver and John Paul Wright, International Journal of Offender Therapy and Comparative Criminology, Vol. 49, No. 4, 2005, 450-71. Address for either: John Paul Wright, Division of Criminal Justice, 600 Dyer Hall, MI 0389, University of Cincinnati, Cincinnati, OH 45221, john.wright@uc.edu.