The bullies at school are found to be problem children not only at school but also at home and the neighborhood. The researchers at York and Queens University found them to be non adjusting with their parents as well as friends.
They also found that targeting those relationships, as well as the problems children who bully have with aggression and morality, may offer ideas for intervention and prevention.
For the study, the researchers looked at 871 students, out of which 466 were girls and 405 were boys, for seven years from ages 10 to 18.
Each year, the kids were asked questions about their involvement in bullying or victimizing behaviour, their relationships, and other positive and negative behaviours.
On asking the questions, 9.9 percent of the students reported engaging in consistently high levels of bullying from elementary through high school.
Some 13.4 percent reported that they bullied at relatively high levels in elementary school but dropped to almost no bullying by the end of high school.
Some 35.1 percent of the kids said that they bullied peers at moderate levels. And 41.6 percent said they almost never bullied across the adolescent years.
After the analysis, the researchers found that children who bullied tended to be aggressive and lacking in a moral compass and they experienced a lot of conflict in their relationships with their parents.
Also, their relationships with friends also were marked by a lot of conflict, and they tended to associate with others who bullied.
Lead author Debra Pepler, Distinguished Research Professor of Psychology at York University and Senior Associate Scientist at the Hospital for Sick Children, said that the findings provide clear direction for prevention of persistent bullying problems.
"Interventions must focus on the children who bully, with attention to their aggressive behaviour problems, social skills, and social problem-solving skills," Pepler said.
"A focus on the child alone is not sufficient. Bullying is a relationship problem that requires relationship solutions by focusing on the bullying children's strained relationships with parents and risky relationships with peers.
"By providing intensive and ongoing support starting in the elementary school years to this small group of youth who persistently bully, it may be possible to promote healthy relationships and prevent their 'career path' of bullying that leads to numerous social-emotional and relationship problems in adolescence and adulthood," Pepler added.
The study is published in the March/April 2008 issue of the journal Child Development.