Let's parse out some of the noise w/ regards to YA vs. adult. This might be a little long so bear w/ me. First, neither category is "better," or "more complex." We should be past that bullshit by now. Plenty of variety and quality, good books and bad, in both categories. (thread)
In recent decades, YA has become a massive and lucrative category. It's clear that there are a lot of adults who like what much of YA offers: fast paced stories tightly centered on teenage MCs. Publishers and booksellers noticed.
Also, young tech-savvy YA authors and readers grew to have a large and vocal presence on social media, further amplifying the category's popularity, visibility, and reach.
So we've seen a "trickle up" effect from YA to adult. Numerous books that are not YA but that employ elements of YA tone or vibe have appeared and done well commercially. The first time I encountered this was in 2014 w/ RED RISING by Pierce Brown.
I saw RED RISING in the adult SFF section but noticed it was compared to Hunger Games on the jacket. Huh. And indeed, it *read* like a YA novel: a fast paced story about a young, heroic MC in a Hunger Games style world. The author wrote it when he was 23 years old.
RED RISING had goofy magic tech like "pulseFist" and the worldbuilding was bare bones. As an adult SFF reader, these were bugs, but for many general readers (many of whom love YA), they are features. That book got a huge publisher push and sold a crap ton of copies.
RR was labeled "crossover." The publisher did not put it out as YA b/c it's not a "teen experience" book w/ coming of age themes, & content wise, it shouldn't be marketed to 12-14 y.o's. YA can for sure have sex and violence, but handled in a different way than in adult fiction.
Remember YA as an official category didn't exist 30 years ago. There's now a whole a generation of new writers who grew up reading YA and absorbing its pacing and conventions. Some of them are bringing that to adult books. That does not make all those books YA, btw.
Publishers know that certain elements attributed to *but not exclusive to YA* - pacing, tight and straightforward linear narrative focus, young (often female) MCs - are simply, well, REALLY COMMERCIAL in any category.
So they put a big push into marketing them online where (adult) YA readers hear about them, read them, recommend them, and confusion further reigns as to the line between YA and adult. Does it matter? For most adult readers, no. It does if you're selling it to a 13-year-old.
I know firsthand about the blurry line b/w YA and adult b/c my first book, ZEROBOXER fell hard in that gray zone. I ended up revising it to be pubbed as YA, but to this day, I'm uncertain about that call. I learned my lesson; I made sure EXO firmly YA, and JADE CITY firmly adult.
You cannot reduce YA to one simple definition. Stop trying. It's not just the age of MC, complexity, or content. It is a combination of factors that speak to a particular target audience i.e. teens. Sure, adults love YA too, but at the end of the day, is the book FOR TEENS Y/N?
That final decision comes from the author, the publisher, and key stakeholders in the YA space: teachers, librarians, and booksellers. It does NOT come from confused readers and bloggers, Twitter, or people who want to denigrate a book by accusing it of being YA.
I love adult and YA fiction. I write both adult and YA fiction. Yes, there *is* a distinction, and it is not easily explained; there are tropes, styles, and conventions that cross freely, and others that don't. But at the end of the day, intended audience is the KEY. /rant over.
