School life can be pretty merciless. Kids have an astonishing repertoire of nasty things they inflict on other kids. But what factors play a role in which kids are the victims and which the perpetrators? Why do some wind up on the receiving end of the nastiness, and others become the ones meting it out?

Psychologists working with Germany's Dieter Wolke at the University of Warwick in Great Britain have analyzed the extent to which parenting styles influence kids’ behavior at school (Child Abuse & Neglect, online). The researchers evaluated 70 studies from recent years in which over 200,000 children had taken part. And according to the results, children with overprotective parents have a higher chance of being bullied.

School bullying is a global problem, the authors stress. According to a World Health Organization (WHO) study published in 2012, about one-third of all children fall victim to the aggressive behavior of their peers. Wolke says that can have long-term consequences for terrorized children that can persist into adulthood.

Children who are bullied often later develop body-image problems, and also have a higher risk as adults of suffering from depression, anxiety or other psychological problems.

The ability of children to get along with other kids their age at school without being bullied, or to defend themselves if they are bullied, is influenced by the way they are parented.

Don't get too cozy

According to the psychologists’ data, children with particularly strict parents, authoritarian parents, or parents who give them too much negative feedback show somewhat higher risk of being the victims of bullying.

The risk is similarly higher for the children of overprotective parents – a surprising result, Wolke says. But it would seem that children from a particularly cozy nest may lack the armor to deal with bullies, the psychologist says. Keeping children away from negative experiences is thus presumably a way to make them particularly vulnerable.

The data from the meta-analysis also reveals that if children are bullied at home by their siblings, the chances are higher that they will be bullied in school.

The kids least susceptible to chronic hectoring and physical bullying, according to Wolke, are those whose parents set clear behavioral rules that must be respected, but who also display emotional warmth and impart a sense of security.

Parents like this also let their kids work out conflicts with peers without immediately getting into the act, Wolke says. This enables children to figure out strategies and develop self-confidence that makes them less vulnerable to bullies.