I second
But I'm not completely ruling out video games as a factor in a child's aggressive/violent nature, but I think it is more about how their parents raise them. If they teach them what is right and wrong, then they will know better than imitating the violence they see in video games. I know many people who have played games like GTA and such growing up and they have not developed a violent nature.
But then again, we are all products of our environment so we are influenced by every aspect of our lives, which also includes video games.