Do video games cause aggression in kids? I doubt it, but as my kids start to pick up the controller I will probably ensure that the games they play are rated for their age.
I think a really bad influence is when kids see programming and commercials on TV that are not related to their age. Commercials for WWF, Ultimate fighting and programming where people hit each other could confuse young minds. I'm talking ages 1 to 7 here, I'm guessing after 8 years of age a kid will have a better grasp of reality vs fantasy.