Ramblings on Librarianship, Technology, and Academia

I would read the hell out of an academic treatise on those books of the late 1970's and the 1980's (when YA was forming as a discrete genre and was still predominantly problem novels) that were marketed to adults but overwhelmingly read by kids and teens. Think V. C. Andrews, Stephen King, Piers Anthony, Anne McCaffery. Probably a good 50% of fantasy, science fiction, and horror. Weird, unashamedly psychosexual drama we mostly hid from our parents. Come to think of it, all four of those authors have written at least one incest story.

Yes, I know there was plenty of adult readership for those authors, but I'd be really curious about the breakdown; I wouldn't be surprised if the teen and child readership numbers dwarfed the adult for some titles.

What changed in genre when people started being able to market a wide variety of genres to older kids and to teens, and sell them successfully? Wither the gleeful psychosexual incest thrillers? What did YA inherit from those books, and what did adult? Do teens still sneak the contemporary equivalent of Valley of the Horses home from the library or is that what porny fanfic is for?