I think there's a crucial point in this book, a subtle twist, and it's not the obvious one that comes a few chapters in, it's one that comes later, close to the end, when our narrator, Rosemary, discusses her childhood memories with her parents and discovers that her memories and those of her parents do not quite match. Things that have loomed large over her life suddenly take on a different aspect. We already know memory is mutable and subjective, in some ways the whole point of the book is Rosemary's version and how it shaped her life. Even knowing this, the scene leaves a quiet sense of shock in its wake.

Of course, the book is about an experiment. The experiment itself seems to do no real harm until it comes to a premature end, and in its ending it shatters a family, warps two young lives and damages two adult lives in ways that are only hinted at. A family is an experiment, of course, and damage is data. We're all primates and we barely understand each other let alone ourselves.

Fowler's writing is beautiful. The book is funny and sad and incredibly readable. It's beautifully constructed and wrestles delicately with big questions that affect us all, about being torn from our basic grouping, becoming alienated and ostracised, and the dangers of reintroduction.