So if I do a story set in England, I can just randomly name characters "Jean" without any explanation because it sounds kind of similar to "John"? Or do the readers have to express an interest?

And I can totally call English people Scandinavians, because who's to say what "Scandinavian" really means? There are cultural ties if you chase the history back far enough, so they can be considered the same!

And they can have turbans, because wearing a turban has happened in London at some point!

Adventures of Jean the Turban Scandinavian Englishman, here we come! He will, of course, work in England's capital, Milton Keynes.