In answer to your original questions-
I always knew I was a little different, but I just recently let myself accept that I was bisexual, if that makes sense. It probably has something to do with the fact that my family basically hates
LGBT people.
Being bisexual just means you can love/be attracted to both sexes. I don't really understand your thinking here. How is it a choice to be attracted to both sexes, instead of just one? Oh well, moving on.
About your brother-
If I came out to my family, I would want support most of all. I would want to be loved for who I am and accepted. You have to understand that it takes tons of courage to come out. You should be there for him, and listen to what he has to say. If you want to ask him questions to better understand it, I'm sure that would be fine.
The main thing you can do is be there for him, and help him through this, I'm sure he's not exactly having an easy time.
I don't think its weird.
I think you're probably here to try to better understand us and get advice on your brother. Nothing to worry about.
You can
PM me any time if you need anything.