The short- and long-term harm done to bullying victims has received much attention lately. The complex web of factors which go into creating bullies are less often discussed.

Every bully does not have the same psychological profile. But understanding the possible factors behind the behavior can help usturn the tide against a deeply entrenched problem.

When my oldest son Alex was 14, he turned into a bully. It started at home, when he would act mean toward his younger brother: teasing him relentlessly, pushing, hitting and scheming to get him in trouble. Later, I found out that he’d hooked up with some other boys in the neighborhood and they, as a gang, had been bullying younger kids.

Here’s how I heard Alex describe one such time. The confession came at a wilderness therapy program we’d sent him to. I was present for a parent meeting at the end of the program.

“I stole about seven bikes and gave ’em to my guys to buy our pot. Oh, and one time I threw a little kid off his bike and took it from him. Then we all laughed at him crying on the ground.”

I remember being horrified. How had my sweet, once-shy and introspective first-born child become this monster?

For my son, the answer would turn out to be complicated, but not unusual. Much later, while working as a psychology writer and researcher, I discovered the many possible factors that can contribute to aggressive or violent behavior in children and teenagers.

At one time, psychologists attributed children’s aggression to their high levels of frustration. Although feeling blocked from having or doing what one wants can lead to aggressive behavior, further study has shown frustration to be farther down the list of causes.

When assessing this large body of research for the book I coauthored with Jack C. Westman M.D., The Complete Idiot’s Guide to Child & Adolescent Psychology, I found the following five factors to be considered most predictive of producing bullying behavior.

1. Physical Punishment

Parents’ use of harsh physical punishment is positively correlated with children’s aggressive behavior. In one 1990 study, peers and teachers rated spanked children twice as aggressive compared with other children. At the same time, not all spanked children are overly aggressive.

University of Tulane researchers studied the effect of spanking using a mixed population of 2,500 children between the ages of 3 and 5. The group included 45 percent who, according to their mothers, had not been spanked, 28 percent who were spanked “once or twice,” and 26 percent who were spanked more than twice. The odds of a child being more aggressive at age 5 rose by 50 percent if he had been spanked twice in the month before being observed by researchers. This 2010 study stood out from others done previously in that investigators accounted for variables, including the mother’s acts of neglect, use of alcohol or drugs, and violence or aggression between the parents.

2. Watching Aggressive Behavior in Adults

Some of the aggressive children in this study were not physically punished. Parents who simply modeled aggressive behavior in front of their children also produced more aggressive children. Such parents tended to use more forceful rather than cooperative means to settle conflicts. They yelled rather than spoke calmly or discussed an issue. They grabbed the TV remote out of someone’s hands, rather than asked or negotiated a peaceful solution to competing needs or desires.

If there is a lot of unresolved conflict in the home, parents can model aggressive behaviors which the child can internalize. Beyond the child’s immediate home and school environment, studies show that poverty and high levels of neighborhood crime create a culture of violence with many negative effects on children. But other factors cut across class and geography.

3. Violent Television

A typical children’s cartoon shows on average one violent act every three minutes. Many young children and teenagers spend more hours watching TV than they do at school. What’s the effect of all this mayhem on growing children? There are many correlational and some experimental studies linking children’s viewing of violent TV programs with spikes in aggressive behavior.

In the laboratory of social learning theorist Albert Bandura, children were given specially created TV programs to watch. In these shows, an adult acted violently, kicking and hitting a plastic doll named Bobo. Two groups of children were given the same doll to play with; one group watched the violent program, the other didn’t. Those who watched were more likely to imitate the on-screen character and act violently toward Bobo than the others.

4. Problems with Processing Emotions

In the 1990s, researchers started to investigate whether any cognitive deficiencies might contribute to a child’s level of aggressive behavior. This work revealed that aggressive boys often respond aggressively because they are not as skilled as their peers in reading other people. They fail to accurately interpret other people’s intentions and when they’re unsure of why someone does something or looks at them a certain way, they tend to respond aggressively.

Another study investigated whether anything could be done to help young people like this overcome their deficiency and be less aggressive as a result. In one correctional facility, incarcerated adolescents were taught how to pay attention to non-hostile cues in a social setting. When they accurately perceived hostility coming their way, they were shown how to use alternative responses. Supervisors at the juvenile correction facility who were questioned after this training program reported less aggression and less impulsivity in those adolescents who had taken the training.

This emotional processing deficit seemed to be a factor present in my own 14-year-old son at the time his behaviors turned aggressive. Here was how he described his state of mind and emotions at wilderness therapy camp:

I’m trying to get in touch with my feelings. I’m having a hard time cause I haven’t had feelings in a long time for some reason. My counselors say it’s the drugs but I don’t know. It seems to me I didn’t have any feelings before I started using either.

As it turned out, Alex’s psychological problems were far deeper than his outward behaviors appeared to reveal.

5. Part of a More Serious Psychiatric Disease Course

A meta-study of 11 longitudinal family studies reveals that conduct disorder puts a boy at a higher risk for becoming an antisocial young man or a psychotic adolescent (J. Welham et al. 2009). I was struck by the number of studies in this review showing that boys who went on to develop schizophrenia had conduct problems when they were young. The word “externalizing” (what many view as “acting out”) is often used to describe their early problem behaviors.

This was the course my son Alex’s adolescent psychological problems eventually took. He was diagnosed and treated for the onset of schizophrenia at age 17, a story I tell in my forthcoming book A Lethal Inheritance.

I certainly want to underscore that not all bullies — nor boys and girls with conduct disorder as children and teenagers — develop antisocial disorder or schizophrenia as young adults. But sufficient numbers of them do to merit a closer look at the deeper psychological currents driving these young people. The general public also needs to develop a more complex understanding of the phenomena of bullying if we are going to stop and treat these young people before they and the children who become the targets of their aggression suffer further.