Coming soon: AboutKidsHealth is getting a new look! Learn more Watch a video tour

print article
For optimal print results, please use Internet Explorer, Chrome or Safari.

Bullying: How it affects those who bully

When data are released about the effects and frequency of bullying, often what is reported are the consequences for children who are bullied. While the effect on those who are bullied should never be diminished, what bullying tends to do to children who bully is also extremely negative.

"Bullying at age 10 sets many of these children on a trajectory of delinquency. It's a red flag for a whole range of problems which often carry through to adulthood," says Debra Pepler, professor of psychology at York University's Faculty of Health and senior scientist at Toronto's SickKids Hospital. "The children who bully are setting themselves up for encounters with the law at an older age. Also, they tend to have troubled relationships from adolescence into adulthood."

Dr. Pepler and her research partners' most recent study tracked nearly 900 students from age 10 to age 18. The aim was to see how bullying behaviour evolved for individuals over time as the children grew. Four patterns were identified:

  • Ten percent of the study group bullied consistently.
  • Thirteen percent bullied at a slightly lower level at age 10 but had stopped bullying by the end of high school.
  • Thirty-five percent bullied at an even lower level but did not give it up.
  • Forty-two percent never or almost never bullied.

Boys were more likely to belong to one of the three bullying groups than girls; however, the study did not specifically examine forms of social bullying, a non-physical type of bullying more common in girls.

Bullying is learned behaviour

The hope is these findings may help identify where intervention programs and counselling will be most effective in stopping what many now recognize as a generational and cyclical phenomenon. Dr. Pepler cites previous research showing that children who bullied often struggled as parents. Their own children tended to bully others. "These are learned behaviours," she says.

Her study found that the children in the three bullying groups were less likely to have supportive relationships with their parents. Elements of a less supportive relationship included high conflict, low trust levels, and poor parental monitoring of the child's activities and behaviour. These children and teenagers also tended to be more frequently in conflict with peers and more susceptible to peer pressure.

Those in the bullying groups were also more likely to be morally disengaged. In other words, they lacked the necessary compassion and empathy to see the negative impact their own behaviour had on others. These characteristics were most pronounced in the group of children who bullied consistently.

Different types of bullying behaviours

While the impact of some forms of bullying, such as actual physical aggression, is difficult to deny, other more social forms of aggression are often seen as a rite of passage: something that all kids have to go though. Most adults, for example, can remember a time when they were teased or had their bra strap snapped from behind while walking down a high school corridor. Dr Pepler is quick to address this issue.

"The impact of harassment depends very much on the individual and the context in which it is delivered. For some, it might not be experienced as hostile but for others, it can be devastating," she says. "It's also not respectful. Any form of disrespectful behaviour has the potential to undermine confidence, identity, and position in the peer group, which is very important."


Smith CA, Farrington DP, Continuities in antisocial behavior and parenting across three generations. Journal of Child Psychology and Psychiatry. 2004; 45(2):230-47.

Pepler D, Jiang D, Craig W, Connolly J. Development trajectories of bullying and associated factors. Child Development. 2008; 79(2):325-338.

Crick NR, Nelson DA. Relational and physical victimization within friendships: nobody told me there'd be friends like these. Journal of Abnormal Child Psychology. 2002; 30(6):599-607.