Children who are smacked by their parents may grow up to be happier and more successful than those spared physical discipline, research suggests.
A study found that youngsters smacked up to the age of six did better at school and were more optimistic about their lives than those never hit by their parents.
They were also more likely to undertake voluntary work and keener to attend university, experts discovered.
The research, conducted in the United States, is likely to anger children’s rights campaigners who have unsuccessfully fought to ban smacking in Britain.
Currently, parents are allowed by law to mete out “reasonable chastisement” on their children, providing smacking does not leave a mark or bruise. These limits were clarified in the 2004 Children’s Act.
But children’s groups and MPs have argued that spanking is an outdated form of punishment that can cause long-term mental health problems.
She said: “The claims made for not spanking children fail to hold up. They are not consistent with the data.
“I think of spanking as a dangerous tool, but there are times when there is a job big enough for a dangerous tool. You just don’t use it for all your jobs.”
The research questioned 179 teenagers about how often they were smacked as children and how old they were when they were last spanked.
Their answers were then compared with information they gave about their behaviour that could have been affected by smacking. This included negative effects such as anti-social behaviour, early sexual activity, violence and depression, as well as positives such as academic success and ambitions.
Those who had been smacked up to the age of six performed better in almost all the positive categories and no worse in the negatives than those never punished physically.
Teenagers who had been hit by their parents from age seven to 11 were also found to be more successful at school than those not smacked but fared less well on some negative measures, such as getting involved in more fights.
However, youngsters who claimed they were still being smacked scored worse than every other group across all the categories.
Prof Gunnoe found little difference in the results between sexes and different racial groups.
The findings were rejected by the National Society for the Prevention of Cruelty to Children, which has fought to ban smacking.
A spokesman for the charity said: “The NSPCC believes that children should have the same legal protection from assault as adults do.
“Other research has shown that smacking young children affects their behaviour and mental development, and makes them more likely to be anti-social.”
However, Parents Outloud, the pressure group, welcomed the research, saying parents should not be criminalised for mild smacking.
Its spokeswoman, Margaret Morrissey, said: “It is very difficult to explain verbally to a young child why something they have done is wrong.
“A light tap is often the most effective way of teaching them not to do something that is dangerous or hurtful to other people – it is a preventive measure.
“While anything more than a light tap is definitely wrong, parents should be allowed the freedom to discipline their children without the fear that they will be reported to police.”
Aric Sigman, a psychologist and author of The Spoilt Generation: Why Restoring Authority will Make our Children and Society Happier, told the Sunday Times: “The idea that smacking and violence are on a continuum is a bizarre and fetishised view of what punishment or smacking is for most parents.
“If it’s done judiciously by a parent who is normally affectionate and sensitive to their child, our society should not be up in arms about that. Parents should be trusted to distinguish this from a punch in the face.”
Previous studies have suggested that smacking children can lead them to develop behavioural problems such as being more aggressive.