It really doesn't matter if a person is born or not born with it, which really is something I don't think any one of us can actually define. The fact is, is that if we believe that people should marry who they want to marry, and that it is a human right. It is in effect denying people their human rights by limiting it to just straights and gays.
You are defining something as rape and against the law for now because the person is not of age, or cannot give what we define as consent, do you honestly believe that will remain the same forever?
By that logic Pedophile sex and rape is consensual in nature.