I'm constantly baffled by the exclusion of bisexuals. I blame bad science, or rather bad scientists. Every year it seems there's a new study on "what makes people gay". Oddly, this is expected to be an on-off switch, and the researchers look in the genes, or the brain or the length of fingers for a sign that one set of people will be queer, now and for always, and another proving the rest will remain 100% straight. It takes a special kind of rigidity of outlook to construct a survey on finger length and decide beforehand there's no middle ground. They then say everyone's "straight, gay or lying" but for that to be true there would have to be an awful lot of liars out there. The last Observer poll on sexual attitudes showed that 4% of people – one in 25 – identified as homosexual, and half as many again identified separately as bisexual.

But this sort of thinking fuels the mythical status of bi people. People are quick to tinker with the definition of bisexual until it's not something anyone would willingly pick for themselves. Bisexuals are supposed to be equally attracted to men and women – always androgyny, but never to trans people – and always at the same time. They supposedly need to have identical amounts of sex with both, and don't notice the differences between them (which might get painful in bed, I reckon). We're all told bisexuality is a phase that everyone goes through and grows out of, and no one's a "proper" bisexual, even though "everyone's bisexual really". Bisexuals are depicted as the monsters spreading Aids, and breaking the hearts of partners inevitably cast aside for a different gender. Who'd want to be bi!

Oddly, the only people not confused about bisexuality are the bisexuals themselves, with groups like The Bisexual Index advocating a clearer definition – they simply suggest anyone who is attracted to more than one gender should consider identifying as bi. It's not about amount of attraction either, just as simply preferring lettuce to liver doesn't make you a vegan.

It's LGBT History Month, so here's something you can quote to people when they ask: "But what have the bisexuals ever done for us?": the first ever gay pride week was organised in the wake of the Stonewall riots in the US, and was the idea of Brenda Howard, an out bisexual activist. But ask around in a local LGBT bar, or group, or event today and you won't find many people out about being bi.

Why don't we come out? A lot of the people using the LGBT scene are bisexuals in the closet – they came out as gay or lesbian because they knew that would get a good reception. But for a bi on the gay scene, the closet has two doors, a bit like an airlock – behind one of them is a cosy atmosphere with no pressure, and behind the other is what appears to be a vacuum.

Of course, it's not actually a vacuum, just seems so by comparison to the loud brash bright lights of the commercial LGBT scene. The bisexuals might not be the celebrities hosting the talk shows and lounging on magazine covers, but they're out there. The kid who sat next to you in class, the driver of the cab you took last Friday, the shopkeeper who sold you the lettuce, your gran's best friend. Maybe your gran. Maybe your partner. If you reread the definition above and think about it, maybe you. Certainly me.

The UK bi scene is out there. It's community-led, with festivals like the regional one-day BiFests and the national three-day convention BiCon (in London this year), and many towns have local bisexual support groups. The big LGBT groups and organisations around the country are waking up to bisexual inclusion too. It's hard work for the volunteer activists pushing it forward, but progress is being made – Brighton Pride is particularly supportive of their local bi scene and the other Pride festivals will hopefully follow in their footsteps.

This isn't a fresh uprising either, this isn't happening because bisexuality is "cool" right now. Next time someone tells you bisexuals don't exist, ask them how old they are. It's BiCon's 27th birthday this year.

Not bad for a phase, eh?