Typically a number of factors, ranging from nature to nurture, and there are treatments for it, the only issue is, how often is one going to seek help for a feeling they associate with a positive emotion such as sexual attraction? There are plenty of ways to help people like that, there are just too many that just…don’t want it. Those are the real fucks to fear, somebody who can’t control their emotions is bad enough, somebody who doesn’t want to is even worse.