OP, some more specifics about the interview conversation might help to clear things up ... in the mean time, more hypothetical commentary ...
regarding whether/when to say something to the school about the interviewer, the sooner the better. and at all the interviews i went on, they always asked for feedback on the interviewers and the interview day. at two schools they even invited us to say "hey, my interviewer was a real scumbag ... i don't feel like i got a fair shake ... " if we felt like that was the case.
regarding the hostile question ... your interviewer asked a question that no one can answer - how did homosexuality evolve? how do we know how/why anything evolved? for example, we know that some people can roll their tongue and some can't. we know that there is a genetic component to this ... research on tongue rolling has delved in to the nature of sibling inheritance and incomplete penetrance etc. ... But no one can say for sure how or why tongue rolling evolved. the question of homosexuality's "evolution" is equally impossible to explain definitively ... and since there is no link between sexual preference and infertility, the whole "wouldn't homosexuality be bred out?" thing is bs. there is, however, lots of research out there that suggests a biological basis for and a heritable genetic link to homosexuality. most studies show that pre-natal hormone levels during brain organization are involved and thus the "genes" involved may actually be mom's. so it is her fault in the end
🙂 Two articles on the subject:
http://www.springerlink.com/content/p2365262023tkn31/fulltext.html
http://www.livescience.com/health/060626_gay_brothers.html
as for your answer to the interviewer's question ... also not that happening, unfortunately. as
LizzyM said, because there's a genetic component to something does not mean that it's not a disorder. in fact, most research on human disease and disorder is around finding and understanding the genetic links to disorders. genetics "prove" disorders to be biologically inherited/predisposed and not just the cause of some lone environmental factor.
none of this really matters though, because simply put, homosexuality is not a disorder. whether inherited, produced by environmental factors or "chosen", it is not a "problem" or illness. there are no direct health/psych issues related to being homosexual, thus it can't be labeled a disorder. there's nothing to "treat." and in response to lukkie, it was removed from the dsm by the same psychiatrists and phd's that wrote the rest of the dsm because research suggested there was a strong biological basis and that it was in no way a disorder ... not to appease the pc public.
Debates in this country around homosexual rights often circle around whether or not homosexuality is a "choice." some folks feel that if it's just a choice - like smoking or being fat or being addicted to drugs or gambling - then it's ok to discriminate. research shows that there's a biological basis for all these things ... regardless, there's no good reason to discriminate against anyone for anything. period.