Exceptionally controversial question, Vanilla.
Polemicists on both sides of the fence maintain stances that are not founded in properly researched studies but are based on anecdotal, theological, or quasi-humanistic doctrine.
Best answer I can give, based on my reading, is this:
One can change the category of people one is sexually attracted to, over time. Few mature women who thought at age 13 that certain of their classmates and several kids a year or two older were hot still have a yen for 13-15-year-old boys.
Given moral imperatives against homosexual behavior and feelings in a given belief structure, it is quite possible for a bisexual to condition himself or herself to believe that the repression of same-sex attraction is God’s gift of change, retaining the opposite-sex attraction, which is “good.”
The handful of ex-gay people I’ve been in communication with in one way or another generally (memory says unanimously, but I’ll leave that open) say that they still feel same-sex desire but “are able to conquer it by the grace of God.” Take that for what you will.
I suspect that a Kinsey-6 homosexual would be able to, at least temporarily, repress all desire on the same self-conditioning basis.
The vast majority of gay and bisexual persons who have “tried to change” have failed miserably, including those who used such things as electric shock therapy. And in that recent study of graduates of an ex-gay program, 66% considered themselves “cured” and 34% had, pardon the expression, fallen back into homosexuality.
My conclusions: Yeah, it’s probably possible. But a long range program, with scant chance of success in any given individual case.
I’d welcome feedback from the gay posters who care to comment.