I came to the conclusion some years ago that I am not actually gay, per se. It's just the currently most acceptable term for the fact I am exclusively romantically attracted to the same sex.
I use the word "gay" to describe myself, because at this moment in history it's useful identifier and framework for emancipatory organisation - we can't fight oppression if we remain invisible to each other and to the wider world, and that's what Pride is about; it's claiming an identity that allows us to exist and to protect that existence from harm.
But if I was on a desert island on my own, I wouldn't be gay. I would just be me. My gayness exists because it isn't heterosexuality, it exists as a contrast to the perceived norm. But were I born 1000 years ago, or 1000 years hence, I would not have had nor would I be needing that label.
One distant day, when we all finally realise that heterosexuality isn't "normal", it's just common, and that most humans exist somewhere else along the sexuality spectrum is the day that gayness will cease to exist, and we will all just be humans. The label is a tool we need now, but already I can see that younger gay people in the UK who have not been criminalised and abused for their sexuality are a lot more "Meh" about their sexual identity, which is far healthier and more productive than the continuous battle for existence and freedom that previous "gay" generations have had to endure.