Teenage fiction is an area that has developed out of recognition in recent years. I can't recall any books written specifically for me when I was that age. Now the range of books increases every year - another reason why so many good writers are attracted to the age group. It is one area where you can still set the pace. For a writer, it's like opening a door in a house and finding it full of unwrapped presents.
Books occupy a very curious position as far as teenagers are concerned.
Although there is no censorship for books for any age group, they have lagged behind the other media in the kind of material they present to young people. The film industry, the music industry, computer games, magazines, comics - they all know very well about the youth market. There is an age group of about fourteen to twenty five that is extremely profitable for everyone. The answer, since children are both teenagers and adults, is probably both. Ask any group of fourteen year olds about the material they have access to, and you'll be in no doubt that the censor is a guide that is largely ignored by children and parents alike.