A discussion about a new science fiction series and the lack of gay characters in science fiction led me to some Hairy Thoughts on the subject.
Going to a lot of SF conventions and reading a lot of SF, it has always seemed to me that a disproportionate percentage of female SF fans and authors self identify as lesbian. But an awful lot of them seem to be of the overweight mannish variety. I have often wondered how many of the claim to be gay in order to seek out other unattractive women for "safe" relationships. If you are unattractive it is easy to want to avoid rejection by the men you find attractive. They are all chasing after the hot chicks. Plus SF offers and opportunity for both male and female gay folks to create and imagine worlds where they fit in.
Of course the primary demographic for SF is young men, so putting in a major male gay character has a very good chance of killing ratings.
Homosexuality is probably a genetically controlled tendency. As with many aspects of physiology and psychology, homosexuality is not a digital function. Most men are primarily attracted to women, but some men are sexually attracted to other men. To a greater or lesser degree. That means that some guys are only going to hook up with gals. Some may occasionally dabble in gay sex and relationships. Some will be attracted to anything with legs. Some will only be interested in other men.
As we unravel the genetic code we will figure out which genes in what combination cause gay tendencies. The next step will be to give parents the ability to select or eliminate different genetic traits. By the time we get to the far future of SF, it is entirely possible that gayness will be eliminated from the gene pool. Possibly it is most accurate to represent a purely straight future society.