I can't tell you how many times I've heard some jackass try to claim that everyone is a little bit bisexual. It pisses me off every single time because, well, for one, they're attempting to tell me what my sexual orientation is, and that, since their assessment is contrary to what I say it is, then I must be lying. And, two, it pisses me off because their statement is not based on any scientific evidence. It's simply an opinion which they are offering up as if it were a fact. But it's not.
Now, I just attempted to look up an actual number to provide you a percentage of bisexuals and, well, I didn't have much luck in doing so. Why might that be? Well, bisexuality is far more complex than just being gay or straight. Some people who are bisexual, may not consider themselves to be such, and will, instead, consider themselves gay or straight depending on the sex of the partner they're with at the time. You also have to take into account that "bisexual" covers a broader spectrum of people than "gay" and "straight" does. Someone who is gay strictly has an attraction to the same sex. Someone who is straight strictly has an attraction to the opposite sex. Someone who is bisexual, though, could mostly be attracted to one sex, and only occasionally attracted to the other. Or they could be romantically attracted to one, and physically attracted to the other.
Now it's getting fucking complicated. Bisexual people aren't necessarily going to be equally attracted to both sexes, like you might think. Though they could be. Generally, though, they're all over the map with their attractions. Complicating matters even further is the fact that, since a bisexual person is capable of being attracted to the opposite sex, they may appear straight to the general public. They could date or marry someone of the opposite sex, and live a completely heterosexual life, while all the while being attracted to both sexes. So, how do you account for this? How often do you suppose this person is likely to admit to their same sex attractions? For some, admitting that can mean the end of their relationship.
I've found, personally, that men seem far more tolerant of their female partner's bisexuality, than women are of their male partner's bisexuality. Similarly, gay men are less okay with their male partner's bisexuality... and, honestly, I have no idea how lesbians feel about their partners bisexuality. So, I'll go out on a limb, here, and assume that they're going to feel threatened by it as well. Straight men like it because it feeds into the common fantasy of watching two women having sex, or the prospect of having a threesome with two women. Right? The women whom I've heard object to their partner's bisexuality have claimed that they viewed their male partner as less of a man, which seems rather sexist. Gay men seem to feel like a bisexual man will be more likely to cheat, but, I've seen no evidence to indicate that that's the case. All of this, of course, is generalization; there are always exceptions.
One article, in Psychology Today, expressed that bisexuals are more likely to explore having a negotiated open relationship. That does kind of imply that perhaps there might be a greater chance of cheating, but I can't say for sure. The only difference between the negotiated open relationship and cheating is the fact that one is mutually agreed upon, and one is not. But, whether or not there's a higher incidence of dishonesty in bisexuals remains to be seen. I can't imagine that there is.
With all of these variations of bisexuality, and with the possibility of so many people being bi but living a straight life, I can only assume that there are more bisexual people than we might imagine; that perhaps the odds are pretty good that maybe even a predominant portion of the population is at least somewhat bisexual. If we take into account those who are, as Dan Savage would say, "heteroflexible," we add even more people to the numbers.
Does this mean that everyone is bisexual? No. I'm not. But here's the annoying part. Who the fuck knows? Bisexuality is such a wide definition that you could go your whole life feeling like you were straight or gay and then run into that one person of the sex which you are not normally attracted to, and bam, suddenly you're bisexual. However, thus far, I'm gay. I have yet to run into a woman whom I've been attracted enough to that I wanted to have sex with her. Maybe when I'm 83 years old, I might meet some lady that turns my crank, but until that point comes, I am, by definition, gay. And no one can, or should, tell me otherwise.
People need to stop making the claim that everyone is bisexual. Or that everyone is a little bisexual. There's no evidence to support that, and when you say that, you're telling everyone around you that you know their orientation better than they do, which is arrogant and presumptuous. So stop that. It does tell us, however, that you are bisexual, and are perhaps projecting your feelings onto everyone around you. So, congratulations on coming out as bi! May you lead a long and healthy bisexual life!