Now this is just plain confusing to me. By this definition, Ulysses and Tropic of Cancer are young adult fiction but a book like American Gods isn't.
Well - I don't think it was meant to be a 'definition' exactly. More than likely, she's just saying that lots of literature written for adults prior to 1960 could now qualify as a teen read, as in it meets much of the other criteria.
This sounds logical, however, consider the case of ASoIaF. Dany, Jon, Arya, Bran, Sansa and Robb are all young-adults/pre-teens. But would you call the series, or even the chapters that concern the children, young adult?
Definitely not -at least, not the whole story. These chapters? Maybe.
The scenario you describe is pretty much a deliberate dumbing down of literature. An overwhelming number of teens in most western countries partake in sexual activities. Similiarly, anyone who has ever gone to school has heard more than their fair share of four letters words by the age of thirteen.
Sexual tension and profanity are both staples of teenage interaction and directly propotional to the amount of realism exuded by a story. Perhaps sanitization of language and actions doesn't matter much in sci-fi/fantasy and can be construed as part of the story structure - but in mainstream or 'coming-of-age' fiction, novels which pupport to be realistic and in tune with the teenage culture, it basically renders the whole premise false.
I don't agree with any of that at all. It's not dumbing down literature if you are specifically aiming for a certain age group. Not all books with a teenage protagonist, or teenage characters, are meant to be read by teenage readers.
And, yes, anyone attending school has heard the four letter words, but that doesn't mean it's ok. It's a little sad that society is constantly pushing our children to grow up.
While sexual tension and profanity are indeed present during teenage years, it's not a necessary staple for all teenagers- either books have it or they aren't realistic isn't a realistic viewpoint. I know of many wonderful, poignant pieces of literature that don't contain sex or profanity that anyone would enjoy, adult and teen alike.
I think one of the things about Ya literature not mentioned is age group. I don't consider Ya just for teens. I think of it as more the 11-16 crowd. Usually, by 16, driving, dating, more freedoms, etc., teens have reached a maturity to be able to handle the grittier subject matter. Some probably do earlier, some later, but if a book is labeled YA I like to think of it as a 'safe' area for any person, able to understand the content, between the above ages. Parents don't have time to police everything thier child is reading, but publishers are able to label a book YA, and hopefully, have some sort of guideline.