"Aren't you Canadian?"
"Aren't you Canadian?" means "I think you're Canadian, but I'm checking to make sure." "You aren't Canadian?" means "I thought you were Canadian and I am surprised to find out you are not." They are basically opposite meanings and the English translation for this should be changed to the latter...
I'm not a native speaker of Chinese, but I have taken a Chinese class from 6th grade all the way through high school, and 是不是 feels more natural than “不是”“吗”. 是不是 is asking for confirmation of something, whereas "不是“”吗“ is basically putting a question mark onto the end of the sentence "You aren't Canadian."
"Aren't you Canadian?" expects a "yes" reply analogous to "Nonne..." questions in Latin. An equivalent question in tone would be "you are Canadian, aren't you?" The opposite is "you aren't Canadian, are you?" which expects a "no" reply analogous to "Num..." questions in Latin. My question is: in Chinese, does the phrase expect a "yes" or "no" reply (or neither) as this determines which English phrase to use.
You can't say "yes" or "no" in Manadarin Chinese apparently, the best you can do is answer "correct" or "incorrect" or, more grammatically correctly, to answer with the verb they used as an affirmative, or as a negative, so to say "不(verb)", such as "have" or "have not" or "able" or "not able".
"Aren't you Canadian" means "I'm checking that my assumption that you're Canadian is correct ." The corresponding English for "ni3 bu2shi4 jia1na2da4ren2 ma" would be "You aren't Canadian, are you?" ("I'm checking that my assumption that you aren't Canadian is correct" or, depending on tone of voice, "On the outside chance that you're Canadian, I'm asking (e.g. because I'm Canadian, too or some other reason that would make you being Canadian particularly interesting to me)).