A 2-year research project by a team at Harvard Medical School could have a massive impact on the belief that game playing can bring out violence in kids.

"Grand Theft Childhood: The Surprising Truth About Violent Video Games and What Parents Can Do" is a new book published by academics Lawrence Kutner and Cheryl Olson.

It is hoped that it will have an impact on the debate as to whether playing games can actually alter everyday behaviour, with some circles blaming highschool shootings on the likes of the Grand Theft Auto series and Manhunt.

"What I hope people realise is that there is no data to support the simple-minded concerns that video games cause violence", Kutner told Reuters.

The project took 2 years and more than 1200 children in the US of A were studied.

And the team took a unique approach - they actually talked to the kids instead of sitting them in front of a console in a lab.

While the team are now being championed by gamers worldwide, their research did find, however, some link between playing M-rated games (so the equivalent of 18+ in this country) and children getting into scraps.

Over half of boys who played M-rated games had been in a fight in the past year, compared to 28% of non-M-rated gamers.

And girls are even worse for fighting - 40% of those who played M-rated games had been scraping in the past year, compared to just 14% for non-M players.

But the team says that these results may just show that aggressive children are drawn to more violent games.

"It's still a minority of kids who play violent video games a lot and get into fights. If you want a good description of 13-year-old kids who play violent video games, it's your local soccer team", Olson said.

The researchers added that parents should be concerned if their daughter is exclusively playing violent games 15 hours a week but for boys, game playing can be a measure of "social competence" or how well they get on with their peers.