Research Update: Bad Boys and Their Genes

I. Topic:

Biological Bases of Behavior--The Influence of Genes

II. Article Reference:

Simonoff, E., Pickles, A., Meyer, J., Silberg, J., & Maes, H. (1998). Genetic and environmental influences on subtypes of conduct disorder behavior in boys. Journal of Abnormal Child Clinical Psychology, 26, 495-509.

III. Overview:

According to Simonoff et al., conduct disorders are the most frequent "impairing child psychiatric disorder" (p. 495). Conduct disorders appear to involve four subtypes: property violations, status violations, oppositional behaviors, and aggressive behaviors. Many adults who suffered from conduct disorders during childhood show continuing personality and psychiatric problems. A range of risk factors appear to be related to conduct disorders including brain damage, neurological disorders, cognitive deficits, and family influences. Simonoff et al.'s study sought to explore the relationship of genetic and environmental influences on the four subtypes of conduct disorder.

IV. General Method:

This study analyzed data made available from the Virginia Twin Study of Adolescent Behavioral Development, which focuses on twins between the ages of 8 and 16 years of age. The basis for Simonoff et al's analysis was mother and child questionnaires regarding certain risk factors and various aspects of different clinical disorders. In addition, the twin method was used to gauge the relative degree to which genetic and environmental factors influenced the presence of conduct disorder. Both analyses used only data from male twin pairs. A multivariate statistical genetic analysis was used to determine correlations between the ratings and zygosity.

V. Conclusions and Implications:

Simonoff et al.'s data suggest that the subtypes of conduct disorder may be differentially affected by genetic and environmental influences. Offspring ratings suggested a genetic influence on property violations and on oppositional and aggressive behaviors. On the other hand, mothers' ratings suggested a genetic influence on only property violations and aggressive behavior. Although this research is still in its early stages, and many questions regarding the the causes of conduct disorder still remain, the data from this study hint that bad boys may be born that way