Haven't They Grown was my first foray into the work of Sophie Hannah and unfortunately, I didn't enjoy it as much as I thought I would. The premise was unusual and certainly had promise but the execution fell flat for me. The book was too far-fetched for my liking and I found it difficult to believe in the characters and their motives. The majority of the book felt slow-paced, with too much dialogue and too many theories as to why the children hadn't grown. Thankfully, the book picked up towards the very end but it felt like a long slog up until that point. I have read many crime and mystery books and this certainly wasn't the best book I have read. I've given it 3 stars solely for the ending but I can't say I'd recommend it or read it again.