In this story (set in the near future), I have a pair of twins that were born in England. They came from a wealthy family and were given a decent education. For reasons that are irrelevant to the matter at hand, they are abandoned in Chicago when they are 11 years old. Again, due to complicated reasons, there is no one they can turn to and they essentially become vagabonds, hiding away from people except when they need money or food or some such thing. As they grow older, they very slowly experiment with limited interactions with people, up to the point where one of them can even be called social. Both twins presumably spend a lot of their time reading, whether its discarded newspapers or whatnot. One writes poetry and short stories. They are now 24.
In this story, they are among a group of five narrators, each writing their own first-person account of what's been happening. My question is, would their spelling still be UK-based, or would it have become Americanized after all these years of reading American publications? I'm curious as to whether 11 is an old enough age to really cement the difference between "realize" and "realise," or if it's one of those things that would depend upon the person.
Any and all help is greatly appreciated.