"So, by that logic -- anyone can decide they want to be gay?"
No. You don't choose happiness. If you look for happiness you won't find it; if you look for God you will find happiness.
OTOH, homosexuals do choose to be homos.
Look, speaking as a straight guy -- I've had some hideous dates. I've been in some nightmare relationships. And I've encountered women that Rod Serling couldn't imagine. But the gay thing was never an option for me.