Sorry to hear about your mate , its such a waste when you loose someone with so much Life ahead of them .
BUT i do beleive that this "parent blame" stuff is bullshit , a person can come from the best house and have had the best upbringing and they could still get in a car with a group full of friends and feel the need to show off and impress people which could always lead to a disaster like this .
I agree that parents do have the responsibility when your younger to teach you right from wrong , but when you turn 18 you have a car you have a licence you should be mature enough to know the difference between right and wrong ...if you dont you shouldnt be on the road at all.