My parents know that I'm not about to go and murder someone simply because I play No More Heroes or Smash Brothers.
Heck they let me play Smash brothers Melee when I was 11. Even then though... I didn't really pick up an M rated game until I was maybe 1-2 months away from 17.... I know it seems silly, but I followed the ESRBs pretty well... sometimes even harshly. (Smash brothers was my first breaking of this rule, I almost threw a panic attack when I found out I had to wait 2 years to do it)
Heck they let me play Smash brothers Melee when I was 11. Even then though... I didn't really pick up an M rated game until I was maybe 1-2 months away from 17.... I know it seems silly, but I followed the ESRBs pretty well... sometimes even harshly. (Smash brothers was my first breaking of this rule, I almost threw a panic attack when I found out I had to wait 2 years to do it)