Smacked children are at risk of turning into aggressive adults, say scientists.
Parents have been warned that slapping or spanking their kids if they misbehave is a recipe for copycat behaviour in later life.
A review of 20 years worth of research found that the more often children were slapped, spanked or yelled at when they were naughty the more likely they were to act in a similar way when they grew up.
"Virtually without exception, these studies found that physical punishment was associated with higher levels of aggression against parents, siblings, peers and spouses," researchers Dr Joan Durrant from the University of Manitoba and Ron Ensom of the Children's Hospital of Eastern Ontario, wrote in the Canadian Medical Association Journal.
It comes just a week after Labour MP David Lammy said last summer's riots were a result of parents being unable to physically discipline their children for fear that social workers would take them away.
However, the authors of the latest review said spanking children could be counter-productive.
They pointed to one study of 500 families that found children were less likely to challenge adults when the parents were trained to stop punishing them physically.
They added that many of the studies found that raising a hand to a child increased their chances of developing mental health problems such as depression.
The authors said doctors should help parents learn non-violent, effective approaches to discipline, as many don't understand what prompts a child's behaviour.
Dr Durrant told MyHealthNewsDaily: "They (parents) are more likely to believe that their child is being defiant or intentionally bad, but in most cases, children are simply doing what is normal for their development."
Techniques include recognising that toddlers tend to say no to everything and ignoring them for 10 seconds when they act up before redirecting their behaviour. Another method is to lay down rules but also explain why they are used.
What do you think? Are there always other alternatives to smacking?