I understand and i agree that its a slippery slope but you have to draw a line somewhere otherwise kids would be trying cigarettes at ten and alcohol at 12. And, you're right, the theoretical science is there but then there are also real-life incidents where a kid snatches a gun from a police officer because he saw it in GTA or a sick kid jumps off a roof thinking he'd 'respawn' with full health, just like in his games.
Perhaps an all out complete ban may not be the answer, but don't you think that some kind of age-related control is required when the stakes are this high?