Neither the Bible nor the ancient Near East had any vocabulary of *orientation* to describe sexuality; sexuality consisted in sexual *acts* (cf. Dictionary of Paul and His Letters: A Compendium of Contemporary Biblical Scholarship article on Sexual Ethics for a discussion).
In ancient Eastern terms sexuality is a choice even if orientation is not if you have to take off your clothes together with another person to do it.
In Western academic terms we have been told behavior of all kinds is wholly determined by genetics (E. O. Wilson's Sociobiology), wholly determined by environment/conditioning (B. F. Skinner's Behaviorism, i.e. NO genetics!), totally free and determined by absolutely nothing (Jean Paul Sarte's Existentialism, from an analysis of the phenomenology of conscious existence -cf. Sartre, Being and Nothingness) [note how these three categorical oppositions are in formal contradiction in their extreme forms] and/or (variously) combinations thereof, or something else entirely depending on what academic departments one tunes out as much as what academic departments one tunes in. There is also the question of biological ambiguity in the case of outliers, e.g. phenotypic females with both ovaries and testes, phenotypic males with ovaries, various complex genotypes other than simple XY vs. xx like Klinefelter syndrome and so on, which is a subject in and of itself (to which I might return). But biological outliers aside, speaking just in terms of the "normal" genotypes/phenotypes, it's typically framed as a nature vs. nurture question as much as a cause vs. correlation question (on the latter cf. David Hume's classical critique of causality as demonstrable via empirical data alone -which is to say it's as much metaphysical as physical question/answer no matter how you slice it "scientifically," which is to say statistically, which let us be frank enough to observe only has two options from the start *methodologically*: i.e. (A) stochastic or (B) determined (there is no C or D -methodologically! Yet even here ALWAYS within a standard margin of error -inescapable in the praxis biological statistics of any kind). Does a given neurobiologist believe, for example, that all mental behavior is causally determined *per se*? Answers and mileage will vary, but obviously if someone says all choice is an illusion he/she will not say behavior or temperament X is a choice. But then do they arrive at their scientific conclusions by a chain of causal determinations, only believing what they "must"? For this reason Sir Karl Popper concluded that determinism of this sort is tenuous as a scientific conclusion ipso facto and would be even if it was actually true.There is always a scientist of the day to say something in the area of behavior and causal determinism that is unsupportable from the perspective of the philosophy of science. It is one thing to say what one believes in this regard; it is quite another to show a particular conclusion is epistemologically inescapable; the latter is quite out of the question from the perspective of probabilism and/or the philosophy of science per se IMO That many practicing scientists due to the need for specialization in their training do not study the latter to a degree of even minimal adequacy is immaterial.
I would say if you're a Christian the wise course is keep your pants/dress/whatever on and your body out of another naked person's bed unless you're married in the traditional manner as the historically/spiritually more recommended course and leave questions of "necessity" of "orientation" to the philosophers and scientists who seem to lack the tools to make epistemologically *certain* (i.e. verificationalist ala classical foundationalism) pronouncements apart from something like a propensity interpolation of probabilistic induction in the first place and simply deal with your own temptations -sexual or otherwise!- under the guidance of your priest, spiritual father or mother etc. and with prayer as best as with God's help you can.