Is homosexuality associated with a green beard effect?

This is just a wacky hypothesis. I don't have any particular evidence that it's true. I’m just throwing it out as a possibility.

A gene can have multiple effects. There is a biological theory called the “green beard effect.” Suppose there were a gene which did two things: (1) caused people who carried it to have green beards; and (2) caused people who carried it to behave altruistically towards people with green beards. It’s easy to see why this gene might be favored and spread through the population.

Now suppose that there were a gene which had three distinct effects:

  1. 1.An increased propensity toward homosexuality. This does not have to be an all-or-nothing thing: merely an increased propensity, subject to influences from the environment and from other genes.

  2. 2.Some other effect which is beneficial to reproduction. For example, suppose this gene tended to cause enhanced creativity and extroverted personality traits. (For example, suppose that successful actors and entertainers had a statistical tendency to be homosexual. This is just a hypothesis.) We can easily imagine that those traits could be helpful to survival and/or mating.

  3. 3.An increased propensity to be revulsed by and desire to persecute homosexual behavior in others. By actively persecuting homosexual behavior, the carrier of the gene prompts other carriers to feign heterosexuality, presumably increasing their chances to reproduce. This is a modified “green beard” effect since the carrier helps other carriers to reproduce, causing the gene to spread. We may not normally think of persecution by relatives as “helpful,” and of course none of us would like to be harassed and abused just so some little bit of DNA could make more copies of itself, but unfortunately the little bit of DNA doesn't care about that.

To recap, the gene has three effects: homosexuality, a major negative from a standpoint of reproduction; a second effect which is positive for reproduction; and a “green beard” effect which helps mask the negative effect. Taken together, the net effect is positive enough for the gene to survive in the population.

This hypothesis has the advantage that it explains widespread persecution of homosexuality, which otherwise must be a puzzle for the determined sociobiologist. From a biological point of view, it would seem more advantageous to tolerate or encourage homosexuality in members of one's own sex, thus leaving oneself with more opposite-sex mating opportunities.