Gay Uncle is Grandmother’s Son

A recent article in Nature talks about naked mole rat poo. This post is not about poo, naked mole rat’s or otherwise. Here is the sentence that triggered this post:

The rest of the [naked mole rat] colony consists of dozens of infertile subordinates that help with tasks such as foraging and defending the nest.

So let’s get to what this post is about: Various “gay gene” theories of (human male) homosexuality and the usual reason advanced against them, which is that the negative fitness impact on its carrier is simply too large for the respective gay gene to spread.

I used to agree with this reasoning for a long time, but it could rest on a crucial mistake. Consider the naked mole rat’s infertile subordinates. How do they pass their “infertility gene” to the next generation? Good question, because being infertile, they clearly don’t.

A solution to this subordinate naked mole rat infertility impossibility problem is to make this an instance of Dawkins’ extended phenotype concept and assume their infertility to be a property of their mother’s genome. Quoting Dawkins (via Wikipedia):

An animal’s behaviour tends to maximize the survival of the genes “for” that behaviour, whether or not those genes happen to be in the body of the particular animal performing it.

By analogy, then, the crucial mistake contained within the usual “inclusive fitness” refutation of gay gene theories is to assume that a homosexual man himself must be the carrier of a gay gene.

Instead, let’s consider that his homosexuality is part of his mother’s genome. Could such a gay gene spread? The naked mole rat seems to provide an existence proof that a mammalian mother can indeed benefit from sterilized offspring.

Looking over Wikipedia’s article on Biology and Sexual Orientation, not only do I not find anything inconsistent with a maternal “gay son gene”, but in fact some of the evidence (such as X chromosome linkage, birth order effects) seems quite suggestive of maternal involvement

I don’t think the idea of a gay son gene (incipient human eusociality?) can be new, but I haven’t seen it spelled out explicitly. If a reader has pointers, please comment.

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