We are frequently asked, "How do you believe someone becomes homosexual?" The question implies that all are born heterosexual and some "become" homosexual somewhere along the way. I believe that implication to be inaccurate.

It is apparent that  homosexuality does not have one particular "cause." It is not purely genetic in origin, for instance, because the very twin studies (Bailey and Pillard) that some interpreted as "proving" a purely genetic origin of homosexuality actually "disproved" it, because only 52% of identical twins of homosexual persons were also homosexual. If homosexuality were dependent on a particular "gay gene," both twins should have possess that gene, and thus there should have been a 100% correspondence.

However, the study (and others like it) did find a highly significant link between biology and homosexuality, as the incidence of homosexuality in the general population is much lower than 52%. Personal experience  corroborates this link because among my homosexual acquaintances I know of several families in which a number of relatives are also homosexual. In one case, for instance (see Gay Sons), a father who believed that he had "become" homosexual because he had been allowed to play like a girl and had grown up without strong bonding with his father tried to make very sure that his son did not grow up gay. So he spent a lot of time with him and made sure that he only played "boy" games with "boy" toys. In spite of all this effort, the son also turned out to be gay.

From my wider studies, I conclude that a person finds him/herself with a homosexual orientation as a result of the interplay of several factors, including heredity, prenatal influence (a controversial subject, but with not only animal studies but some human studies to back it), and environmental factors such as childhood trauma or being brought up and conditioned as a member of the opposite sex. The latter is the background of a significant number of lesbians, for instance.

Ultra-conservative Christians and gay theologians appear to agree that a genetic origin of homosexuality has moral significance. Ultra-conservatives claim that homosexuality has no basis in genetics and is therefore a morally culpable choice. Gay theologians argue that homosexuality is genetic and is therefore morally correct. I disagree with the basic reasoning. Hereditary tendencies may be toward morally positive or negative behavior. The fact that I inherited a strong streak of selfishness and a bad temper does not sanctify these traits, for instance. While we are not responsible for our heredity,  we are responsible with what we do with our heredity. And the Bible teaches that to whom much has been given, of that one, much will be required. So God requires no more of one than the other -- a daily submission to His will. (Luke 9:23)

While there seems to be strong evidence to point to a biological link to a homosexual orientation, it is also very likely that, for some people, a homosexual orientation develops as a result of psycho-sociological factors. In other words, for some, homosexual orientation may be altogether environmentally caused. (Conservative Christians have generally taken the stance that all homosexuality is environmentally caused.) I believe this to be especially true of lesbianism, as there is little, if any, evidence to point to genetic origins. Yet, environmentally caused homosexuality is not experienced any differently than genetically caused homosexuality. In either case, persons find themselves with an overwhelming desire to be intimate with members of the same gender when the whole world says that the normal attraction is to the opposite gender. Despite the testimony of some in today's generation who say they experience no feeling that this is "wrong," I believe that most, if not all, homosexual persons do experience this feeling. Thus, these people do not choose to be attracted to the same gender any more than the rest of us have chosen to be attracted to the same gender.

In summary, homosexuality is not "caused" by a choice. Some heterosexual men choose to engage in homosexual encounters and then go back to their wives and the enjoyment of a heterosexual lifestyle. The young man who serviced their needs in some public washroom simply shakes his head in wonder that such a thing is possible, for he cannot conceive of such a choice. Several of my homosexual friends have acknowledged that they know men who have chosen to engage in same-gender sex exclusively -- and thus appeared to "become" homosexual. But this is not the case for the majority. In fact, not a few homosexuals are somewhat judgmental of those they call "bisexual" -- people who can relate sexually to either gender and enjoy it.

For a balanced overview of the subject see "What Determines Sexual Orientation?" (off-site link on the Canadian Ontario Consultants for Religious Tolerance site)