I did some experimenting when I was about 13 - 14 and I'm definitely heterosexual. But I have this theory I'll attempt to explain ...
All women are curious about other women, in one way or another. We've all heard that it's not men we dress for, but other women. You've probably heard men say that they love how beautiful we are without makeup or the latest fashion. So why do we have to dress just so and wear the makeup?
Women, unlike men, don't have to be gay to see another woman and admit that she's gorgeous or has a stunning physique. We hear boys talking about sex and conquests from our early teens.
We begin, at a young age, to think of one another as sexual objects, perhaps even competition. We're always sizing up other women and commenting on their looks. And the more we become in touch with our own sexuality we begin to compare ourselves to other women, especially if any of our men have told us details about what satisfied their other women.
We start thinking along the lines of
I wonder how that could have felt good to her when I prefer it this way which might slowly progress into something like
I wonder if she touched me, she would know how to do this without coaching and so the thoughts are in motion.
These are just a couple of thoughts that float through my head. Yes, I do have a fantasy involving a woman, but I was much happier keeping it as a fantasy, describing the scenario to my guy because he loved to hear me talk about it in bed.
Sometimes, fantasy is better than reality. But if anyone feels unsettled, as though they may be missing something, there's only one way to find out, right?
One more quick thought -- You can't pick what religion, nationality or race you'll fall in love with. Who says you get to choose the sex of the one you fall for?