Yes it is a choice. This is my opinion as a heterosexual. The most frequent response is this...
So, you chose to be straight?
Yes. I did. And I continue to make that choice everyday. I could choose to be homosexual any day.
How did you do that?
Because I look at women, fantasize about them sexually/romantically, and I pay enough attention to them to fall in love with them. All the actions I have just described I can do also to men. But I choose not to. Let's say that in order to prove my point, I decide to become homosexual... tomorrow. I can start the process of that by doing the following...
Looking at men. Fantasizing about them sexually. Paying enough attention and searching until I find one that has traits that I can live with for the rest of my life. There is no internal drive that will stop me from doing any of these things. My eyes aren't going to avert themselves. My mind can imagine anything I put to it- a two-headed elephant or a man's naked body touching mine. You can do it too. There is nothing in my mind that, by default, prevents me from imagining anything.
As far as sexual arousal, that's the easiest part. Turn out the lights, relax your mind, and allow yourself to be touched. You habits and social programming may scream "No" but if you can relax, and of course you can train your mind to relax just like you can tolerate a colonoscopy without punching the doctor, then your mind will "listen" to the pleasure signals that the nerve endings in your skin are sending to your conscious mind. After all, the nerve endings send signals the same regardless of who is touching you. It's not like the nerve endings themselves say... "Whoa! Hold on, that is a man's appendage. Change the signal!" No. The skin doesn't know. Any averse reaction is the product of habit, social programming and identity, which are all temporary and changeable things.
The next response I always get is....
So you're bisexual?
I'm saying we are all bisexuals. We just choose to live as heterosexuals or homosexuals at certain times, or even the whole time. Some people can identify as heterosexual in their teens, have hetero relationships, then years later change to homosexual and have strictly homosexual relationships. And again, years later, in their 40's or 50's, change back to heterosexual. Looking at the entire life span, you would say that person is bisexual. But for those periods of 10-20 years, he/she was either living as a heterosexual OR a homosexual.
Any one can do this. Both love and sexual arousal/attraction are results of how much attention we pay to others. And there is no internal drive that limits how much attention or what kind of attention we pay.
Well I've been gay all my life and no matter how hard I tried to be straight, I just couldn't do it.
My response to that is you did not try hard enough, on a long enough timeline, nor do you open your mind to the possibility of being sexually aroused by a female's touch (allow the skin to send those signals to your conscious mind) nor to the possibility of paying enough attention to a particular woman's traits, and seeing the merits of spending more and more time with her, even falling in love. If you only pay attention to men, of course you will not find a woman you could romantically love. If you don't relax and open your mind to the pleasure, then of course your mind will filter out the signals her fingertips are sending to your central nervous system. "Ew! A woman is touching me! Stop it. I'm gay!"