I am ONE HUNDRED percent with you on this. I'm the same age with the same problem. I mean it's just blood and language. No racial offense to anyone, but I AM BLACK. I am exposed to more stuff in REAL LIFE than in a video game. I could go to school and hear the equivolent of 2048520985209852 M rated games. And just as much violence too. My mom has no problem with movies, but a SERIOUS one with video games (**bleep**?) . And it's not like I'm 11 or something. No amount of sexual content allowed in a video game could even come CLOSE to what I've experienced in life. Fact of the matter, I think this is rediculous. Why don't they make the ratings E- Everyone T-Teen (13+) M-Mature (15+) and then R-Restricted (17+). Then they can make more people happy, sell more, and QUIT RUINING MY LIFE.
I've made a little progress just recently. I asked for their specific problem with (just in example) shooting games. They said it was the fact that blood splatters and they look like they're getting maimed. So then I suggested like uncharted 3, or MW3 since you can go to settings and change the blood/gore settings. I say the best thing is work around their prefences to begin with. Give them NO EXCUSE to say no. Then once you have one, it's make or break. Either they see it's not that bad and cave and become more lenient in the future, or see something they don't like, and **bleep** you to eternal censorship.
On the other side, if you are underage, suck it up, ratings are there for guidence, like alcohol, it wont necesarily ruin your childhood but to some people it might cause serious damage