It is so easy to blame video games, music or movies instead of bad parenting. I am 37 years old. My first "R" rated movie was Friday the 13th: Part II. That was roughly 22 years ago. I have sense never developed a desire to go on a killing spree.
The violent video games came around after I was an adult, but I see no difference between the video games and the music videos or heavy metal music that was around when I was growing up. At the time, Ozzy Osbourne and Blue Oyster Cult took a lot of heat for their songs.
I may be wrong, but I believe you have to be awfully weak-minded to let entertainment influence your choices on whether or not to commit violent crimes. It seems that every generation tries to blame the easiest target.