It is. The second year after he had some problem with religious freaks, he spent the summer writing a presentation for each book. He loans the file to the parents at the beginning of the year, so they can note down books they object to their kid reading. It's after that some parents started giving him books.

I don't know where this all comes from... despite my parent's encouragement (without being pushy) my brother disliked reading (or anything that involved sitting down for long) until he was 17-18!

I know he also likes a lot Scandinavian youth literature (not necessarily the classics) but I have no idea which writers.

I think one reason for the anglo-saxon slant might be that the offering from continental Europe/Asia is perhaps fairly poor in English (if adult books are anything to go by), combined with the fact the offering for kids in English is large, probably the vastest there is.

I don't know about this. "Exception" makes it probably too narrow. I think this is indeed very common in the "big readers" category. It's not curiosity for "grown up" stories that's lacking in kids that age but reading skills. It's more reading a lot that is not the norm. When you do read a lot, it's perfectly normal that your reading skills increase much faster than the average. A lot of stuff passed by me at the time, but it's never worried me. In fact, that too probably stimulated a great deal my curiosity for History (among other subjects). I was lucky to grow up in a house where I could simply go to mom or dad if I didn't understand something (as this all was all long before you could google stuff up).

I guess a lot of parents (especially in the US) would disagree with what my parent let me read at that age, though. Even here many of mom's more religious friends didn't like how little she restricted my reading choices, or the fact she said stuff like she worried about sexist books, but not books with sex.