Yorkie said:It was never marketed as adult literature. The parents nicked it off the kids and then started buying it for themselves.
I didn't start reading it until book 3 came out but got hooked on it.
I think Yorkie is right. I became hooked when I read The Philosopher's Stone to my grandchildren. I've since read them all and hopefully the latest book will arrive by post from Amazon tomorrow.
I'm over 60 - so that should put me in the clear.