Can you just suddenly become gay?

I think I did. I don't know. It's just weird. I read that a lot of gay people have always known or always were and just figured it out. I don't think I did.

In my family (they are very conservative), I was raised with the belief I would be straight. I always thought I was but I was never very attracted to girls. Not like my friends. I had two girlfriends before because I was supposed to. That's what guys do right? Anyway this summer I met this guy. He's like 2 years older than me almost. We hung out a lot and we had fun and all that. But then he kissed me, just out of thin air. And all I wanted to do was kiss him more. We haven't seen each other since summer ended since we go to different schools in different towns but I keep thinking about him. I want to see him shirtless (that happened a few times when we went swimming) and I think about having sex with him but I don't know. This just suddenly happened and I don't know what I want. Well I do. I want him. But it's weird.

So can that happen? Can gayness just like pop up like that?