Choice vs born-with-it isn't a valid reason. If science discovered a way to change your sexuality, would you be OK discriminating against gays after-all? Religion is also protected and nobody is born with a particular religion. Country of birth is something that people are born with but we heavily discriminate against that - a Syrian can't just get the plane to America and go set up home there. You Americans will almost unanimously agree to stop him for no other reason than an accident of birth.