You can explore the results for yourself by reading the published research, but without getting technical there was simply no conclusive evidence between violent video games and increased aggression in the 2,000 British 14 and 15 year olds taking part in the study. The researchers conceded that games can provoke "some angry feelings or reactions", but that's a considerably different take-away than the idea that the video game itself is conditioning the player towards violence.

It's all about how you phase the question and answer. Does playing violent videogames make a person more violent? Likely not, but then again, I don't think that is what most people think. Does playing violent videogames make a person more aggressive, short-tempered, and crude? Like other studies, including this one have shown, the answer is likely yes.

Mind you that the study used 14-15 year olds, people just barely not old enough to play M rated games. Would you let your 8 or 9 year old be playing an M rated game thinking that it won't affect them at all?