Is Homosexuality a Disease?
My model – not the only possible model based on a pathogen, but reasonable – leans on a couple of natural examples. One is narcolepsy. We now know that narcolepsy happens when a particular kind of neuron, concentrated in a little region in the hypothalamus, somehow gets zapped. 99% of narcolepsy cases happen in the 25% of the population that has a particular HLA type – which suggests that something, probably a virus, triggers an overenthusiastic immune response that zaps a neuron subpopulation that produce a particular neurotransmitter (called hypocretin or orexin) that regulates appetite and sleep patterns. And it doesn’t do anything else: narcoleptics aren’t stupid. You can compare narcolepsy to type I diabetes or Parkinson’s disease. Suppose there’s a neuron subpopulation that performs a key function in male sexual desire: wipe out that subpopulation, and Bob’s your uncle.
If so, homosexuality is comparable to deafness in that, as a kind of defence-mechanism, people people build up a sense of identity and community around their dysfunction. But obviously a parent would want to find a cure early on if at all possible. Some parents claim to be proud of their gay children, but that doesn’t make much sense. I have a hard time imagining that the news your child won’t be giving you grandchildren isn’t a huge disappointment for most people.
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I’ve generally assumed that homosexuality is often a function of some hormonal imbalance during pregnancy. Cochran doesn’t seem to address this even in the comments, and I’m not sure why. He does say that “identical twins are usually discordant,” and maybe that’s relevant.