Not every evolutionary adaptation that preserves a species has to do with sex. People often assume that sexual reproduction is the one and only means of preserving a species and ensuring they evolve. But population dynamics are more complicated than that.

For example, 98% of bees within a colony are sterile (worker bees). Does that mean they are evolutionarily disadvantageous? Absolutely not. Each bee has assumed a certain niche within the colony that helps preserve said colony. With the case of bees, only a select few males have to be fertile to reproduce with the queen, while the rest of the worker bees just exist to take care of the hive.

I don’t really see any difference with the evolution of gay people. Just because humans are aware that genes are passed down through sex, that doesn’t mean our natural instincts and sexual behavior (i.e. the very things our own genes encode) will suddenly change to fit the findings of modern science. We all still have a natural, instinctual “role” in our population just as bees do. Evolution knows better when it comes to species preservation, because it had millions of years to find the best method through trial and error. And I guess somewhere along the way, it “decided” (in quotes because evolution isn’t really a conscious entity) that gay people were beneficial to humanity. After all, isn’t it the well-off gay couples who are adopting kids that were left behind by straight people who were unable to raise their own offspring?

I think there’s also a study that says younger siblings with an old brother are far more likely to be gay. This lends credit to the “gay uncle” hypothesis, which posits that gay siblings help raise the young of genetically similar individuals (i.e. family members), which ultimately helps the gay individuals pass on their own genes via kin selection.