Thank you for being civil.
I chose after experiencing attraction for both genders. I understand what you are saying about "those people are probably just bisexual", but I think actually discerning that for certain is difficult because it requires a person to be introspective enough to understand the difference between their choice and their desire. I'm very introverted, so introspection is all I can really do well.
If I had the desire for same gender relations, but chose to get rid of that desire, and it's really gone now, is it gone because of my choice, or because I wasn't done developing? Or due to some life event that affected my psychology? Or what-have-you. There's just not enough information to discern that effectively & reliably imo. I only know what I've experienced.
From my perspective, there are 3 things related to sexual relations to be considered: Biological reaction, i.e. blood flowing and whatnot, emotional reaction, i.e. desire to fornicate, and psychological action, i.e. "I'm going to have sex with that person." Usually biological & emotional are tied together, but if I just experience the biological, but not the emotional, is that relevant to what sexual orientation defines?
I personally always thought sexual orientation was purely based on your choice of who you fornicated with when I was growing up. Then, as the LGBT movement has grown, I've come to understand that what most people view that as is "what you are sexually attracted to", and not "what you actively sleep with". I'm still lost on the definition of actual sexual attraction though. Does it mean the emotional response, the biological response, or both/neither, and it appears most people consider the psychological choice irrelevant now-a-days.
For me, it's always been a choice. It's hard for me to understand how it's not one for others, but I didn't live their lives, so yeah. I'm just a bit perplexed at how so many people are certain of something that science has yet to point to in any significant or meaningful way, according to the bodies studying this very subject intently.