Every age in society brings its peculiar “biases.” I’m not speaking here of social prejudices, but rather of prefered fields of study which assumptively, by their prominence, color all discussions. This has been recognized by historical analysts for eons.
Thus, the Enlightenment period brought a “prejudice” toward Reason, which is not necessarily a bad thing, just an acknowledgement that Reason was the central organizing prinicple. In the 1970’s it was the field of psychology that was elevated to near-sacred status. If you were really “modern” you had at least your own therapist, if not a psychiatrist instead or in addition; and if you were a poster-child for psychology you also attended weekly group therapy. Psychology was so popular that it overran itself, in that psychology programs became overenrolled and produced a glut of psychologists on the market, many of whom found themselves unemployed and eventually changing careers.
In the early 21st century here, it’s medicine. The tendency, therefore, is to view every human behavior through the “determined” or determinable lens of medicine. Well, if your physiology determines your behavior, then your culpability (for anything) vanishes. Because it’s a slippery slope from saying medicine determines just “some” behavior: Why not all behavior? Maybe I have an inborn genetic tendency to lie, or to steal, or to murder. We get the same problem with popularizing medicine that we got with popularizing psychology in the '70’s: sloppy “science.”
Genes, and brain configurations, shape initial tendencies – not just sexually, but in a whole host of potentialities – interests, temperament, every variety of attraction & possibility. However, the infant is still in many respects a “tabula rasa.” Environment is huge in the formation of the individual, and anyone who doesn’t understand that hasn’t read enough (no, not science), but biographies. It’s patently clear, when you do enough wide reading, that there are thousands of people who would have, might have, turned out quite differently, given innate tendencies and even circumstances of their births, had it not been for positive, unusual, countervailing, etc. influences after their births. That includes, btw, many people who were probably bipolar (their biographies exhibit that) before we had a name for it, Borderline Personality Disorder before it was supposedly determined that it was a “hopeless” diagnosis, people who were clinically depressed (to the point where today we would consign them to little expectation of living a productive life, but rather consign to “disability” and 24/7 meds); in fact, many artists, especially the body of classical composers, were then, and are today, subject to depression.
Medicine as determinism is first of all junk science, and second of all, toxic to humanity. But the worst of all is limiting the complex phenomenon of sexuality to the field of medicine. Sexuality is not just, or even primarily, medical. If you don’t know that, you haven’t done much reading. Sexuality depends on so many factors and influences that it can hardly be confined to genetic determinism. That is so obvious merely by looking at varieties of behavior in various societies over time (including today), and by chosen behaviors in subcultures such as prisons.