I believe it is totally fine that Tweens such as me myself are reading books for 14, 16 or even 18 year olds. The thing is that the current generation children know A LOT of inappropriate things which we should not be knowing through internet or other things. So, what is the point of hiding things from the child? Anyhow it's anyways going to know about soon. I'm not proposing that we should tell a child everything at once, but a twelve year old is mature enough to understand things. And if you think that reading these. Kind of books is going to ruin a kid's childhood then NO. It will enhance their vocabulary. Of course, learning a few bad words along the way. But we can't pretend that they will never know about it for life. Because one day, they will. To end my part of this debate, I would like to quote an unknown personality but the words are true "Reading is dreaming with open eyes."
I'm not really against it, but I do find it irritating when you find a twelve year old reading "Fifty Shades of Grey". Oh, its a book about how women let themselves get whipped when they're a 21 virgin who looks 36.