Well first of all you of course need to make clear why you don't feel like you could fit in. If you did not like the "type" of persons there just say that, they are not my type of people which I feel comfortable with. If it is the ambience you dislike you need to figure a way to describe that in words, it could be that there is a very stressfull ambience you don't like or that there is a very "frictional" ambience you don't like (the whole campus is divided into groups…the emo's the tough guys, the nerds etc). Furthermore it could be the case that you don't like the way they teach at Fordham, you could say that as well. Most important is however is that it is your life and thereby your decision where you are going, also if you feel you don't fit in just say it exactly like that. Rankings don't say so much, there are wonderful smaller universities out there you could go to whom fit you more, and that is the entire point. It is not about you just saying no not that one, next. No not that one, next etc. It is about whether you feel good about the place. You need to find some example universities you want to see, go there with your parents and if you notice something you like there, just tell them straight away, that university might even be cheaper so that can be a argument too. last but not least you could also notify your parents It does not fit your intrests, show them your site about algorithms etc, show them what you are intrested in!
Well I hope any of this can help you. More or less it comes down that you need to do some research for yourself, find some examples compare it with your parents, visit other places and if you notice something you like there tell it to your parents (same goes for disliking) You just need to make clear WHAT you want to do and WHAT you are intrested in. make a paper list, what is your ideal university like? visit some campuses, and compare them to your ideal university. A month or several weeks later you might also renew your list, perhaps you saw something you liked extremely well, just put it on there! In the same manner you can make a negative list, the worst university, compare this as well. Talk with some other students so that you get a good idea of what is going on…
Ok…i'll take a breath.
Hope it may serve you well :P