Whether you view sexuality as a choice or an inherent quality is very important to this issue. People will firmly stand on their belief (and without conclusive evidence it can only be a belief) that a person is inherently “orientated” a specific way and cannot and should not try to change it. The person has no responsibility for it because they are deemed not to be in control of it. The problem in that belief is that if you believe you have no control over something you tend not to waste your time or energy trying to change it.
My sexuality is a choice. I choose to be heterosexual every day and that is an easy decision for me. I never really entertained homosexual desires; as a result that's not really an issue for me. I also choose to be faithful to my wife every day - in thought, word, and deed. This is much more difficult for me because many past years of entertaining wrong heterosexual desires (which were as harmful to me at the time as homosexual ones would have been) was actually encouraged by the society I grew up in. I choose daily with God’s help to make my desire for my wife alone and to the exclusion of all others. I choose not to entertain desires that are contrary to the covenant I have made with my wife and when I fail it is God who helps me to return and reassert my commitment to our covenant (Matthew 5:28 and 15:19).
People get so caught up in making their emotions the definer of their identity but emotions are fleeting and unreliable. Desires and emotions are good servants but poor masters (Jeremiah 17:9).
If I started calling myself Han Solo and every conversation I had was about Star Wars trivia, all my clothes were related to Star Wars, and I refused to date any girl who wasn’t dressed like Princess Leia, you would probably say that I had an unhealthy obsession. If you then started calling me “the Star Wars nut”, you would be defining me by something that ought not to be the entirety of my life; you would also be strengthening my identification of myself on those terms. As a result, I would come more and more to think of my own identity as inextricably entwined in my Star Wars fandom.
If someone were then to tell me I have an unhealthy Star Wars obsession, I would be angry at them because they were trying to take away a vital part of who I am. I would be unable to contemplate my life without Star Wars. You might say that my affinity for Star Wars is just a part of who I am, but consider whether I would still be me if I had lived in a place or time where I did not get the opportunity to see the films? If I made a conscious choice to put aside all of my Star Wars gear and focus on a career instead, would I still be the same person then? A person is much more than the sum of their desires.
In the same way, a person who sees themselves as gay can see their sexuality as an inextricable part of their personality. In fact many straight people see their sexuality as an inextricable part of their personality, and fail to see that they have an unhealthy obsession that takes up too much of their life. My belief is that this is largely a result of our society being wholly too preoccupied with sex and with the media in particular using sex to get our attention.
As far as the biological versus optional nature of sexuality we could also have the same argument about alcoholism in my family. My father habitually over- indulges in alcohol and I know that I am predisposed toward that same behaviour (whether you believe that is emotional or biological) but it is my choice to put aside the childish desire in favour of a higher ideal of properly controlled moderation.
You could suggest that my weight problem is just the same, and that the answer is to put aside the desire for self-gratification in favour of a higher ideal and simply learn to make better choices and embrace properly controlled moderation. I would probably agree with you (on a good day). It doesn't make it easy to do.
Because it's difficult or because I have relapses, or because I sometimes convince myself that I don't really care about it and should just eat what I want, doesn't mean that I am biologically predestined to be overweight. It means that I have not fully matured in this area of my life, and still have some spiritual and emotional growth to come.
My point is that I have an urge or a desire for something that is, at its heart, a good thing, but my experiences and my brokenness gives it a tendency toward the distortion. God gives us the desire for food because we need food for sustenance but more importantly he meant for us to enjoy good food. It should be a pleasurable thing for us to be able to enjoy a good meal with friends or family. This desire gets corrupted into excessive self-gratification; desire for more food than the reasonable amount (that which we can burn with our usual exercise) or the wrong types of food (highly processed and full of unnecessary chemicals and sugars).
The same is true of sexuality. God meant sex for procreation but also for enjoyment. The desire for sex is not just to get us to have children but to bind a married couple together in bringing satisfaction to each other. The desire gets corrupted into excessive self-gratification; the mistaken belief that we need more sex more often with more people, or the wrong people (not just homosexuality or philandering but also a number of other less socially popular choices).
I believe our sexuality is a choice we all make and there are many who have made the choice to change in favour of a higher ideal testifying that they are in control of the choice. There are also many who struggle and fail. Can it be possible that some make a choice and others are biologically predestined? You might suggest that the person who claims to have taken control of their sexuality and changed their “orientation “ is simply denying who they really are and is doomed to fail miserably (in more than one sense) and end up like the others who tried and failed, or failed to try. But if they show themselves to be truly changed then this would seem to be a question more of the person’s ability (with God’s help) to deal with their own emotions and desires and tendency to succumb to them: an outright war against the ubiquitous immorality and self-indulgence of the culture around us rather than a war against the tyranny of their inherent genetic structure.