This is a fascinating book about a small village on future Earth where children switch gender each year until having to choose "Male, Female, or both?" upon reaching adulthood. Part of the story is unlocking the mystery of that setup, but that's not the major part of the book (or it wasn't for me). Instead it's an interesting "what if?" to examine gender roles, belief, and traditions.
While it exists as part of the larger League of Peoples series, this could easily be read as a standalone novel.
I will note that the Open Road Media ebook, just like Expendable before it, suffers from the ebook having been scanned from a physical copy. Many scanning errors were left in the book, with the worst ones being ones that even an automatic spellcheck would have cleaned up, like "3ther" instead of "other" and "Doit" instead of a character named "Dorr." There are 20+ of these and each one is a distraction from the story. My contacts with the author and Open Road Media regarding the ebook errors for Expendable received no response, so I won't bother this time.