What would the childrens book world look like if Harry Potter had never popped into J.K. Rowlings head, as shes described it, fully formed? Hypotheticals are never easy, but a Harry Potter-less world well, thats just about impossible to conceive.

By the same token, untangling Rowlings influence from the greater arc of childrens literature over the past two decades is a fraught task. Her Potter saga inspired frenzied release parties, staggering numbers of pre-orders, millions of words of fan fiction and, as it stands now, nine feature films: Its an easy assumption that this seminal series fundamentally changed middle-grade and YA fiction.

And it surely did. The market for these kinds of books, especially fantasy, exploded during the early aughts, as Harry Potter took off. Not just lightweight series like The Baby-Sitters Club or one-offs like The Fault in Our Stars, either; publishers began offering kids blockbuster series like The Hunger Games, Twilight, and Divergent. Then again, plenty of authors were already offering well-crafted fantasy and realism for young readers. What can really be laid to Rowlings account?