Joseph, you are chronically quick to accuse people who disagree with you of heresy. I wish you would stop that. (Never mind, he or someone else erased his accusation.)
Martin is asking a valid question and I don't think either of you are really paying attention to the question itself.
First of all, of course what we do is affected by the influences around us (or they wouldn't be called 'influences'!). Remember, train a child up in the way he should go and when he is old he will not depart from it? Training, environment -- these are incredibly important in a person's life. One does not simply make a choice out of the blue: I think I will be a homosexual now. Or I think I will be a thief now. Things influence these choices. There are, one way or another, 'invitations' or temptations toward these areas. If not, then all who rebel against God would be homosexual, but they are not.
Is there a biological element involved? I don't know. And, quite frankly, neither do you! I do know this, however, that even if there is a biological element involved, it is not one which is overpowering but one which can be overcome when one chooses to follow Christ instead of one's own sin nature. The Holy Spirit gives each us of the the power to conquer whatever our own particular points of weakness were/are where sin is concerned. We were not all adulterers. Not all murderers. Not all homosexuals. Not all liars. Not all thieves.
We each had our own 'specialties' where sin was concerned! Whether or not there is a genetic component in any of these is not known. It's as simple as that.
But we do know that there are strong social and psychological influences which direct the sinner toward one or another 'speciality.' For instance, it has been documented past any shadow of a doubt that violence on television and other forms of entertainment engenders violence in kids. Is this added to a genetic predisposition to be violent? It may be, as not all kids who indulge or who are allowed to watch these things turn out violent.
Not every child who is homosexually abused becomes homosexual. But some do. Why the difference, assuming none of them are saved? We don't know.
Martin, if I have missed the boat on what you were trying to discuss here, please let me know.