SMACKED kids are more likely to turn to violence, booze, drugs and suicide as adults, experts say.

Other physical, sexual or emotional abuse has similar effects.

Nearly a fifth of people had harsh physical punishment as kids and half were maltreated, a study of 35,800  Americans found.

Dr Tracie Afifi, of the University of Manitoba in Canada, said: "Studies have examined physical punishment and antisocial outcomes mostly within childhood or adolescence.

"For example, studies have found that spanking was associated with increased aggression, behavioural problems, antisocial behaviour, and externalising behaviours during childhood.

"Adults who demonstrate antisocial behaviours may experience many difficulties in developing and maintaining positive relationships, have trouble sustaining successful employment, and have problems with the law, among other challenges.

"Anti-social behaviours are generally found to be more prevalent among men compared with women, again making the examination of sex differences an important consideration."

She said strategies to prevent adult violence should focus on children.