Perhaps I'm naive, but I went to another institution of higher learning just down the street from MIT. I was physics major, and I was not aware of any cheating among my peers. Again, perhaps I was oblivious, but my impression was that high performing students were not cheating, whereas there was a lot of cheating among lower performing students. This pattern made sense to me at the time, because it seemed that the students that wanted to learn challenged themselves, took hard classes, and wanted to do their own problem sets and actually learn the material (we were all card carrying nerds and proud of it!), not just get a good grade for the sake of some future reward.