The pattern was even stronger among girls, with 40 percent of those who played M-rated games having been in a fight in the past year, compared to just 14 percent for non-M players.

One of the most surprising things was how popular mature games were among girls. In fact, the "Grand Theft Auto" crime action series was the second-most played game behind "The Sims", a sort of virtual dollhouse.

Kutner and Olson said further study is needed because the data shows only a correlation, not causation. It is unclear whether the games trigger aggression or if 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.

Photograph for representational purposes only.

Photograph: stock.xchang