Just getting myself caught up on all the things I've missed, since I've been away from the forums for a few months and saw this. Not sure why it's a new thread, since it seems like there is a longer history to this?
That said, maybe I can help-- human sexuality is one of my specialties and there seems to be some confusion. To start off with human sexuality, there are a few points I feel are important to keep in mind:
1. Despite a serious lack of education on this matter, there are actually many different ways people can experience attraction to one another-- for many (if not most) people, these attractions often come together, forming a "matching" set of attractions. However, for some people, their attractions vary depending on the "type" of attraction, creating "mis-matched" orientations. To help clarify, I'll address a few types of attractions and then provide examples.
Sexual attraction: the desire to have sexual relationships with other people. Triggers for this attraction can be connected to any of the senses-- sight, smell, touch, sound, etc. This is when someone sees another person and is "turned on" by them.
Romantic attraction: the desire to have romantic relationships, but not necessarily sexual in nature, with other people. The "love" feeling, when people develop crushes or romantic infatuations with one another.
Sensual attraction: the desire to have physical, but not necessarily sexual, relationships with other people. Someone may strongly want to cuddle, hold another persons hand, or just have physical touch.
Aesthetic attraction: the desire to experience other people on an aesthetic level, appreciating them like artwork. (Wanting to look, but not necessarily touch.)
Someone might be sexually attracted to men, but only romantically attracted to women-- they would find that they want to have sex with men, but can't form close bonds with them. (Or maybe they can only see them as friends.) Someone might be asexual, sexually attracted to no one, and aromantic, romantically attracted to no one, but have a very strong aesthetic attraction to people with certain traits.
This can obviously get really confusing for people trying to figure themselves out, because we don't teach that there is a difference between these attractions. Generally, it's considered that all of them come in a package, and you're either straight, gay, or bi. When things *don't* come in a package for you, you don't know which one you are.
2. Behavior is not indicative of sexuality. Because people are complex, and there are societal factors at play, people do not always *behave* or *act out* their attractions in a straightforward way. Some factors might be... Loving someone romantically, even when you are not sexually attracted to them; internalized shame about ones natural sexual desires; enjoying sex physically even without attraction, not understanding there is a difference between feeling in the nerves versus sexual attraction, which is more mentally connected; lack of sexual education in general; etc.
3. Some people have completely unchanging sexualities throughout their lives, while others experience changes in their attractions. It's not that they have chosen differently, it's that their attraction naturally changed on its own. People who have never experienced such a change may think people who do are "picking something different" or "were hiding their sexuality before." There isn't any evidence to show anyone ever picks who they are attracted to, and a decent amount of evidence showing strong biological ties, so moving past that... For reasons stated in item 2, sometimes people are either unaware of their sexuality, in denial, or are deliberately hiding it. Other people just naturally changed over a period of time. No one but the person themselves can really say one way or the other, though.
As for the discussion on bisexual people, I think part of the miscommunication was that bisexual people are ones who identify as straight and then later identify as gay (or the other way around.) Bisexual people (or pansexual people) are attracted to multiple genders, so even if a bisexual person is in a same-sex relationship for 10+ years, that relationship ends, and they begin seeing someone of the opposite sex, they have not changed from gay to straight-- their attractions did not change, only their behavior. Sometimes people *do* identify as one or the other, and then identify differently, but that goes back to point 3.
In any case, human sexuality is extremely complex and fascinating. There is so much experts don't know, and so much misinformation among non-experts! Sadly, there is also a lot of misinformation flying around from experts in non-related fields endorsing their views on human sexuality, when that is not even their field of study. XD For some reason, this is tolerated-- even though a biologist stating their opinions on, say, engineering would not be taken so seriously. Maybe it's because some people see it as a moral issue instead of a science? Who knows.