Of uality and blindness?

We all know that people are born either heteroual, , and aual. But what about those people who are born blind (like Helen Keller)? How can they say that they are attracted to a certain if they can't see it? How can a blind man say that he's physically attracted to girls if he haven't seen girls yet in his life? I'm a little bit confused about this but I think it sounds interesting.