I'd say absolutely, so long as the kids can also be mature about it and obviously realize that it's part of a game, and not reality (fucking anti-gaming fear-mongers, I'm looking at you). I would actually rather prefer a ~14 year-old to play an M rated game if they were doing it for the story of the game, rather than a ~20 year-old playing one just because of the gratuitous violence, nudity, or to scream profanities/t-bag during online play, because the latter obviously reveals that they are less mature than people 6 years younger than them. That said, of course, parents should ultimately be the ones making the judgment calls on what they think their kid(s) can handle. If they know their kid is nowhere near mature enough, then they obviously shouldn't get those kind of games for them, but if they feel their kid is mature beyond his/her age, then I would say go ahead and get them it. Same thing happened to me, and my parents made the right call to actually let me play M rated games, watch just about any movie (including the porn issue, which they didn't freak about), and read books with mature content all when I was 14-15, mainly because I demonstrated to them that I acted incredibly mature and reasonable compared to basically everyone else at my school. Now, if said parents are way too overprotective, then chances are, those odds of making a valid judgment call go straight out the window, and for which, I wouldn't blame a kid under those conditions to actually get a hold of these games to actually have fun once in a while.