I don't really see how this is even a political question.
For a politician... when it comes to issues on sexuality, gender and access to rights and facilities, whether or not you believe that someone is inherently how they present themselves does matter.
Why does this matter though? Supposing that people could decide to be gay in a vacuum, why should that have any effect on their ability to access rights and facilities? It would still be discriminatory to allow firms to punish them for a lifestyle choice that is inconsequential and damages no one.
That's one way to look at it. Another way would be even if they are "born that way", why should the rest of society be forced to accommodate their ways which go against our morality? They should have the same rights as everybody else, including marriage to the opposite sex.
And black people should have the same rights as whites to marry others of their own race! Such logic, wow.
Do you understand how insulting and degrading this statement is to me and others like me? That you would compare your inconvenience at being forced to live alongside people who are born different from you to what gays have had to go through? Show a little empathy, man.