In regards to your last question, not necessarily. Being sterile is indeed a biological problem, yes, however I don't see it as big of a problem as homosexuality. Homosexuality is a lot more than missing a few reproductive properties since the two organisms aren't compatible for reproduction at all. Also, I would say it is slightly immoral to marry them (the sterile significant other) over someone who is able to produce children. I would like to continue my family name and culture, and continue to produce for my species.