Can You Beat Conduct Disorder Into Children?

According to Jaffee et al. (2005), we may very well be beating bad behaviour into some children rather than out of them. In “Nature X Nurture: Genetic Vulnerabilities Interact with Physical Maltreatment to Promote Conduct Problems”, researchers found children with high genetic risk of conduct problems were more likely to experience symptoms of (or be diagnosed with) Conduct Disorder (CD) when exposed to physical maltreatment. And while the paper discusses heritability, environmental interactions, and how the two interplay, it also generates a multitude of questions and possibilities.

Genetics, Conduct Disorder< and Conduct Problems

After completing e-risk longitudinal studies with monozygotic (MZ) and dizygotic (DZ) twins, each child was assessed using 14/15 DSM-IV symptoms for conduct disorder and for zygosity. They found children with CD diagnosed MZ twins were 24% more likely to exhibit conduct problems if exposed to physical maltreatment, while those with a non-CD diagnosed MZ twin were only 2% more likely. Genetic factors accounted for 58% of the variation in CD symptoms, while environmental factors accounted for the rest. The research included many other interesting points as well.

The experiments conducted by Jaffee et al. addressed many of the biases often encountered in these instances. Maternal reports were verified against teacher reports. Oversampling compensated for the inevitable loss of participants. Researchers weighted the data to reflect the British population. And twins were tested away from family to maintain consistency. This doesn’t eliminate all possible biases of course.

Questioning Jaffee’s Genetics and Conduct Problem Study

In addition to the issues covered in the limitations section, other possible biases could still be present. For example, choice-supportive and obsequiousness biases are possible. As humans, we tend to fall into the trap of trying to make others see us in a better light. Alternatively, we can fall into the modesty bias where we blame failures on ourselves while attributing the good things to the situation. It is possible that we can become desensitized to violence and poor home situations to the point that they don’t seem as serious to us as they do to others. Hindsight bias could also potentially play a role in skewing the results of interviews and reports.

Aside from that, the science behind genetics, brain plasticity, experience, and environment can also complicate these results. For example, parental abusers will sometimes target one child over for various reasons. While weighing both twins as the target helps negate this, watching someone be abused can have drastic effects on the brain. Also, shared and non-shared environmental factors have various effects on behaviour and brain structure. We don’t know which one occurs first. And, when one area of the brain changes, it can have drastic effects on seemingly unrelated area. This study looked at females who gave birth to their first child before the age of 20 to ensure high risk participants were included in the study, but throughout the study, the role of fathers, parenting styles, and other related factors didn’t seem to be addressed.

This piece of research is a fantastic springboard for future work. For example, it would be interesting to see how these results vary between cultures. Also, it would be interesting if the same degree of GxE interplay holds true for children with ASD, ADHD, and other complicating factors. As noted in the paper, these findings could also help reduce costs of preventative and intervention programs, as well as help redistribute resources to those who are at the highest risk of antisocial behaviour and conduct disorder.

Citations/Additional Information:

Jardine, C. (2008, June 20). Dave Pelzer: ‘You Don’t Get Over It, Just Accept It’

Reilly, K., & Born, M. (2014, July 21). “a href=””>Experts Say Some Children Are Singled Out for Abuse While Siblings Left Unscathed.

Allen, S., & Daly, K. (n.d.). The Effects of Father Involvement: An Updated Research Summary of the Evidence (Rep.). University of Guelph.

Scott, S., Doolan, M., Beckett, C., Harry, S., & Cartwright, S. (2012). How Is Parenting Style Related to Child Antisocial Behaviour? Preliminary Findings From the Helping Children Achieve Study (Rep.). UK Government Department For Education.

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