I'd say that geeks tend to think about their environment a lot more than other people because geeks tend to think about systems in general. I have never encountered a rational argument for homophobia. Gay people seem to me to be just as likely to be virtuous or decadent as straight people. Discriminating against people for having a different sexual orientation seems totally irrational to me. As far as I'm concerned,…
From parents and close relatives it is easy to see a evolutionary reason. However from unrelated males (more common) it would seem that they would have every reason to encourage homosexuality in other males. Maybe it comes from when most people who lived together were related.