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And the last thing is my kids know that not every book is a "keeper". You run across duds. So we check out more books than we need and are not afraid to just abandon a book that is drudgery and look for a book that is a better fit

Yes, I agree with this. We bring home tons of books. DD starts some and doesn't finish. Oh well. On to the next book.

I would say, keep strewing his path with a million different kinds of thing. Graphic novels, high-level nonfiction, magazines. As polarbear points out, also don't underestimate the power of peer pressure. One thing that worked in our house even thugh it wasn't intentional--have a parent visibly enjoy a children's book you think he might like. DD was adamant that she wasn't going to read Harry POtter (it's scary, it's about a BOY, I'm tired of hearing about it)--and then my DH decided to read the series, which he never had. She saw how enthralled he was and couldn't resist. She's about to start book 5.