I'm not sure I completely understand this question.

I do think sexuality is fluid for some people, but I definitely don't think your sexual orientation can change just because you want it to??? Which is what it sounds like you're asking.

Sorry I meant how for say, in your teenage years, your hormones are to the roof and there are all of these changes to your body that make you get excited over basically everything. Once it calms down, you are not attracted to the same 'things' anymore.

I think your hormones can come into it, yes, and I also think that some people's sexuality may change at some point in their life. But you can't change it yourself (as in, it's not by choice). You can choose what you act on, though. For example, a bisexual person might seem (to other people) to be straight if they only date people of the opposite gender. Dating people of one gender though does not stop them from still having feelings for the other.

I'm not sure if this only happens in your teen years though, or if your orientation can be fluid later in life too once puberty is over. So I do think hormones can be the cause of orientation fluidity for some, but I'm not entirely sure if that's the only thing.

Agree with sarabeara and glelsey.

For a long time I just thought I was straight, even after I fell for a girl, but over time I realized that I was bisexual.

well, yes and no depending on what you mean??

i mean, your orientation is not something you can control, so yes, but it's also very possible for it to change at some point because orientation is fluid (ie: you could be bi one day and end up being pan later on)