Are we all a little bit gay?

I once kissed a girl. It was New Year’s, I was in Edinburgh and surrounded by a guy-on-guy, girl-on-girl, girl-on-guy kiss-fest of epic proportions –and I wasn’t about to wreck the moment.
That said, the pash planted on me by a dear gal-pal was a bitter disappointment: the kiss was too soft, too wet and waaaaay too far from the stubble and grrrr factor I’d come to like about kissing guys. It was all wrong. I found myself craving beard rash like an old friend.
That kiss was an eye-opener. I'd always thought there was some weight to the theory that we're all a little bit gay, especially as I like ogling gorgeous girls as much as guys do. Now I think it’s just because a) I appreciate beauty in all shapes and sizes and b) I can't quite shake my girly competitive streak.
Getting back to the debate that rages, though, whether we're gay or straight or bi or at liberty to chop and change willy nilly (pardon the bad pun) is one I never get bored of. A formerly married male friend informed me last night that for many guys, it wouldn’t matter if a guy or girl was going down on them – it’s just a blow job. While I wasn't entirely surprised to hear his point of view - I once dated a very straight guy who admitted he’d received a BJ from a guy and liked it – I know just as many straight men who’d die rather than let another guy toy with their tackle box. I have male and female friends who spent their teens experimenting with same-sex relationships, swinging back to hetero when they hit their 20s. Are they gay? Or bi? I know those in their 30s and 40s who still aren’t sure where they sit on the gay/straight scale. I’ve heard of happily-married spouses who suddenly decide to switch teams; I know people who are definitely one way or the other, and yet more who loathe labels and get shirty at anyone who uses them.
What’s your view? Have you ever experimented? Would you? If you’re gay, when did you know it – and was there ever a time in your life when you quite happily had hetero relationships?
The ‘anonymous’ button was made for posts like these, folks.