Ever since I let my 8 year old son play Grand Theft Auto IV he has become extremely violent?

That is weird not all kids get like that over a video game the best behaved child ive ever met has been playing rated m video games since about 7 years old, i guess its just how emotionally mature the child is. I don't think a video game should be to blame or you for letting him play it, maybe something eles is going on with him you might not be aware of.