In your case, you might be in a group of bisexual people, who can chose a sex to identify with. This actually can make all the sexuality subject a bit muddy to understand. If you extrapolate your feelings on other people you can come to the conclusion that everybody can make similar choices. The problem is that most of us can't. For example, I'm a strictly hetero man. I never played with dolls, though I had access to, and I never cared about women clothes either. Pretty much from onset of puberty I immediately knew I was sexually attracted to women only. Nobody taught me to be attracted to women, nobody taught me how to pump my blood to my penis to get excited when seeing a woman. The reaction was always spontaneous, often surprising (when in wrong moment), uncontrollable and simply automatic. No choise. This could be only explained by my brain being hardwired to recognize feminine beauty as sexual beauty. Also, I never fantasized about touching other a man, being in relationship with a man, kissing a man. I never had smallest erection looking at naked handsome young man. Never. No choice again. Obviously no man sexual beauty compartment in my brain to activate my desire for them.
Now, I can easily understand a gay man, who by design of his brain, have brain architecture in sexuality compartment like a women. In this case he will get sexually excited seeing young handsome man, not a woman. He will have no choice. You see, we all carry male and female brain "schematics" in our genes. Y chromosome makes male brain to be built a bit different than female, and this includes sexual department. Which tells you which sex to be attracted to. Genetic mistakes happen very often and it is conceivable that some people will have mixed female/male mixture of brain architecture. This problem was exacerbated in humans due to arranged marriages in the past. Even intolerance against gays in previous decades. I know few gays that still pretend to be hetero in their relationships. I know few from my high school who never had girlfriends and eventually became priests. I also know couple who finally stopped pretending and divorced to live with boyfriends. I know many of these people from way back, and I doubt that they made a conscious free choice to become gay.
Who would want to make their lives more difficult, go against family, religious preaching, becoming laughing stock of neighborhood, being beaten up by bullies, harder to find mates, and create problems having children, if they had a choice?
Even if epigenetics has something to do with sexuality, it is still genetics, and give no choice to individuals.