Humans have always been known to fear what they do not understand and we all know that as well as these "superhumans" would have. It would not take long for someone to realize that they were different and most people tend to try and hide their differences. In a world where people get murdered for something as simple as what football/soccer team they like, their sexuality or their political beliefs, no one would want to stand out and shout about having "magical" powers. Besides, we are all taught about the witch burning back in the day from a relatively young age. 

But no, I was thinking it would be more like an instinct than an actual fear. Like how birds instinctively fly away whenever something comes close to them or how we instinctively draw away from something that hurts.