My instinct is that it is, but DS is simply not interested.
I've posted on the Books section, and tried lots of the suggestions, but they just don't grab him.
He went from Roald Dahl and Horrid Henry, to Beast Quest and How to Train Your Dragon, but that's it. Doesn't like Enid Blyton, Michael Morpurgo, Harry Potter, C S Lewis. Just tried the Roman Mysteries, but found them boring.
He reads Horrible Histories, Science, Maths, endlessly.
Very able at reading and English (teacher reckoned level 4b at end of year 3), but I do wonder whether his Literacy will suffer if he doesn't read fiction?
School not remotely worried, btw.