Ok, I posted this on another board a long time ago, and it seems appropriate here. I've even done a little illustration just for Pixies! Essentially, no I don't think everyone is really bi, I just think everyone's unique
It's the CasperTG Theory of Sexuality, at least that's what I call it so it must be true.
It's all about sexual preference, and how it's viewed. At a very basic level, sexuality is divided up into either Heterosexual, or Homosexual. That was probably the commonly held view up until perhaps mid 60s or so (just a guess).
Then people realised there were bisexuals - people who liked both genders. So there were three categories of sexuality - gay, straight and bi. I'd say that's probably the common way of thinking now.
I think the next stage to understanding sexuality was originally proposed deades earlier by Kinsey, but is only now starting to catch on popularly. That's the 'scale' of sexuality. I think Kinsey had it at -5 is totally gay, no interest in the opposite sex at all, and +5 was totally straight, no interest in the same sex. In the middle at 0 is absolute bisexuality, with an equal preference for men as for women. And in between are the various grades. +4 for example, is mostly heterosexual but has thought about a same sex experience.
But I think there's one more stage of sexual understanding, a way of thinking that not many people have fully grasped. I think that sexuality is truly and individual thing, and labels are if anything counter-productive. Gender is just one small component someone's overall sexual makeup. For example, just say I like have anal sex and be the 'giver'. I may like to give more to men than to women, so be it. But that's just for that one particular act - I may have no interest in any other sexual act with men. And that applies to every act - maybe I like to receive blowjobs from women, but not men. But I like to suck cock, and I don't like licking pussy. I'm not sure if I've explained it very well, but what I'm getting at is that gender preference is just a small component of someone's sexuality and it can be completely variable for every act, for every person, for every situation.
And attached is the special - just-whipped-up-on-the-spot illustration for Pixies.
It's not necessarily true for me, but it's close enough. The stronger the red, and larger the circle, the more I dislike or am not turned on by that act. On the other hand, the stronger the green and larger the green the more that floats my boat.
Notice how "Likes to suck cock" is much higher than "Likes to lick pussy". But I'm not gay, because my numbe rone is "Likes to fuck pussy". But I'm not totally down the line bisexual, either.
And then consider that this is PURELY about physical sex. When you start putting emotions into the mix, and intellectual attraction? That's just a chaotic whirlwind that no shrink in a hundred years will fully understand.
I hope at least some of this made some sort of sense. I understand it much more clearly in my own head!