IMHO, having not seen the article, I'm biased toward the idea that there is a non-causative correlation between homosexuality and population density simply because having more people in an area increases probability of homosexual interaction. Homosexuals are more likely to accept their sexuality when they're not "the only one" and have support.
And this was debated in the class. The class was Developmental Psychobiology taught at Rutgers, by the now retired Dr. Gandelman (hope I'm remembering him. Its been years. I might be confusing him with someone else).
I also mentioned the study where homosexuality appeared to be correlated with increased stressors experienced by the mother.
One theory proposed is there is a critical stage in the development of a male where there is testosterone exposure that masculinizes the male brain while in utero to 1-drive the person to desire females, and 2-create a male personality/identity.
Cortisol as some of you may know disrupts the production of testosterone. So as I mentioned, the examiner hypothesized that women while pregnant that were stressed were more likely to have homosexual male children.
Unfortunately that study could not be replicated. It turned out the examiner was able to identify the correlation of bombing in WWII to specific German towns and the incidence of homosexuality because Germany used to have a registry of homosexuals. This practice has long since been banned because it was an invasion of privacy, and from what I understand and remember (which may be wrong--remember its been years) that the registry was an artifact from Nazi Germany, and the Germans just took some time to get rid of the law.
But taking that theory a step further, and assuming the study was on to something, several in the class debated that possibly increased stress with a pregnant woman may have an evolutionary advantage in terms of a community or family vs the individual with having homosexual children in terms of overpopulation. Humans usually compete with each other, not against other animals in the food chain. Increased stress before modern culture could have been from overcompetition with local humans. It could have made one group of humans survive better in terms of a community vs other human communities.
As for other theories (that I remember), there were studies that females born from male & female twin pairs were more tomboyish. Why? The theory is the testosterone produced by the male twin carried over to the female twin during development and masculinzed the female's brain. There actually was some data supporting this. E.g. tomboyism was measured by behaviors that male children prefer over females such as playing with male oriented toys, playing sports etc.
This lead to a further theory that male & female twin pairs may increase the odds of lesbianism in the female. However from what I remember, the examiners weren't able to measure because they did not follow the female subjects long enough.
Its all interesting, and this is one of the reasons why I feel psychologists truly have some better training in aspects we psychiatrists don't. I've never seen anything like this examined by psychiatrists. Remember we are trained to treat mental illness based on a medical model, they are trained to understand the human mind. That's a big difference. While I was a psychology major, all my training with cortisol, or oxycontin, and other hormones were with the perspective on how it affects behavior and emotions, while I never saw one psychiatrist that had that level of knowledge unless they too were trained in psychology or studied it on their own outside of a psychiatry curriculum. Don't you think that we psychiatrists could benefit from having that knowledge?
As for the overpopulation data, from what I remember this data was also present in several animal models. There also were several other negative aspects with overpopulation (as interpreted by the number of people in a given area of space). More crime, more dirtiness (pollution/garbage/sewage), higher basal rates of anxiety etc.
As mentioned above, there were several factors that could have distorted the studies. For example, a male female twin pair--with females more likely to be tomboys, that could also be explained by the female having a male twin. Maybe she played with his toys because they were as readily available as female toys, while in a lone female child, she would only have been bought female toys by her parents.
I don't know if any researchers re-examined these issues, discounted any of them, or added more to them. After all I was in college back in the mid 90s! I'm sure there's more data more now than back then.
