Quite by chance, I've read several books lately that are meant for adults but feature child characters. The more I think about it, the more common this seems. Think Oliver Twist. Yet the ones I've stumbled upon are all literary novels told in the first person, coming-of-age stories for those already long in the tooth, perhaps hoping to recapture the mystery of youth.
Specifically, in the last year I've read David Mitchell's Black Swan Green, Olive Ann Butler's Cold Sassy Tree, and Sandra Cisneros' Caramelo. I don't know what to call this genre, do you? Can you think of other examples?