This amazes me to this date as I am an avid reader of a wide selection of books, magazines, etc. I'm not trying to make anyone feel guilty. I'm suring you're doing great with your little ones. But the fact remains that very young childen can learn to read, and it is a heck of a lot of fun teaching them how.
Children vary in the norms of development, from the age they start to walk, talk, read, etc.
Not all children are ready to read at the same time, same age and at the same speed. But that boys loves to look at his words. Just because he can't speak, doesn't mean he's not learning word recognition.