Children who are exposed to negative parenting – including abuse, neglect but also overprotection – are more likely to experience childhood bullying by their peers, according to a meta-analysis of 70 studies of more than 200,000 children.
The research, led by the University of Warwick and published in the journal Child Abuse & Neglect, found the effects of poor parenting were stronger for children who are both a victim and perpetrator of bulling (bully-victims) than children who were solely victims.
It found that negative or harsh parenting was linked to a moderate increase in the risk of being a 'bully-victim' and a small increase in the risk of being a victim of bullying. In contrast, warm but firm parenting reduced the risk of being bullied by peers.
The study authors, Professor Dieter Wolke, Dr Suzet Lereya and Dr Muthanna Samara, called for anti-bullying intervention programmes to extend their focus beyond schools to focus on positive parenting within families and to start before children enter school.
Professor Wolke said: "The long shadow of bullying falls well beyond the school playground – it has lasting and profound effects into adulthood.
"We know that victims and bully-victims are more likely to develop physical health problems, suffer from anxiety and depression and are also at increased risk of self-harm and suicide.
"It is vital we understand more about the factors linked to bullying in order to reduce the burden it places on the affected children and society.
"People often assume bullying is a problem for schools alone but it's clear from this study that parents also have a very important role to play.
"We should therefore target intervention programmes not just in schools but also in families to encourage positive parenting practices such as warmth, affection, communication and support."
The study categorised behaviours such as abuse/neglect, maladaptive parenting and overprotection as negative parenting behaviour.
It categorised authoritative parenting, parent-child communication, parental involvement and support, supervision and warmth and affection as positive parenting behaviours.
Professor Wolke highlighted the finding that overprotection was linked to an increased risk of bullying.
"Although parental involvement, support and high supervision decrease the chances of children being involved in bullying, for victims overprotection increased this risk.
"Children need support but some parents try to buffer their children from all negative experiences.
"In the process, they prevent their children from learning ways of dealing with bullies and make them more vulnerable.
"It could be that children with overprotective parents may not develop qualities such as autonomy and assertion and therefore may be easy targets for bullies.
"But it could also be that parents of victims become overprotective of their children.
"In either case, parents cannot sit on the school bench with their children.
"Parenting that includes clear rules about behaviour while being supportive and emotionally warm is most likely to prevent victimisation.
"These parents allow children to have some conflicts with peers to learn how to solve them rather than intervene at the smallest argument."