It is certainly easy to classify John Wyndham's The Chrysalidsas old school YA fiction, from before YA fiction needed a label, but it offers more than your average after school special between covers in that it treats the reader as an intelligent and reasonable person, and that while there is a touch of the 50s to the book, it was certainly way ahead of its time.
David Strorm is the only living son of a patriarch of an ultra-religious post-apocalyptic community. Faced a level of mutation in the their farming stock, both plants and animals, the community has twisted the christian faith into a fundamentalist view that any variation is a sin against god and must be burnt. This is handled by the community and by appointed inspectors. A few plants that don't quite grow to perfection and a whole crop is burnt to the ground. While this may have helped a little curb the proliferation of any mutagens that may be harmful to humans, it has certainly held back any natural selection processes.
Unfortunately the rules do not end at the farm. Any human born not in god's image is not certified by the inspectors and is taken, hushed up and forgotten. There is also an unspoken rule that a female who produces offspring three times that do not get certified is taken away and quite possibly treated like the livestock that also do not produce. It is a frightening and terror filled community, one that brings back memories of Atwood's A Handmaid's Tale.
So everyone in this community has a stamp of approval that they fit the image of god in all their looks. But what happens if there is a variation that an inspector cannot see? David learns from an early age that he can communicate with a small group of others telepathically. This small group of children band together in their fear and strategise to hide their differences in fear for their lives. But all is changed when people notice their strange behaviour when one of their kind is hurt and they come to their rescue with no seemingly way of knowing that the person was injured.
At a guess I have probably read The Chrysalids about a dozen times. Mostly in my teens as I worked my way through whatever John Wyndhams I could find in my local and school libraries after discovering The Day of the Triffids. So any John Wyndham is a comfort read for me. A mix of good sturdy SF with nostalgia. Truthfully this book probably deserves a 4 star rating, but it means a lot to me. It was the Wyndham that made me that much more confident as a teen who did not fit in. It introduced me to religious fundamentalism. And it also made it OK to be a daydreamer. I think all the John Wyndhams that I read as a teen have made me a better person in the long run. I certainly wouldn't be the same person had I not read and loved them.