According to this maternal immune hypothesis, cells (or cell fragments) from male fetuses enter the maternal circulation during childbirth or perhaps earlier in pregnancy. These cells include substances that occur only on the surfaces of male cells, primarily male brain cells. The mother’s immune system recognizes these male-specific molecules as foreign and produces antibodies to them. When the mother later becomes pregnant with another male fetus, her antibodies cross the placental barrier and enter the fetal brain. Once in the brain, these antibodies bind to male-specific molecules on the surface of neurons. This prevents these neurons from‘‘wiring-up’’in the male-typical pattern, so that the individual will later be attracted to men rather than women.
From what I read on the topic, it's much more complicated. People have plenty of typical-female or typical-male parts of brain slushed around, generally people tend to have the most of them that correspond to their gender (IIRC you can guess gender/sex correctly about 80 or 90% of the time by looking at the brain).
It may contribute along with other factors for the cases where the brain does express gender dysphoria.
So really, I don't personally believe a brain can be cleanly male or cleanly female. Rather, if specific parts are formed differently than usual, then they respond differently to external stimuli. This can result in a wide range of sex-atypical behaviour ranging from mere homosexuality to finding one's genitals revolting. How you interpret that objective phenomenon is really up to the individual.
Though I also do agree that gender dysphoria can have many different expressions, once you drop gender you get into a whole new world of stuffs where people hate various things about themselves (I've met people with self-described "whole body dysphoria" who are generally okay with their gender and simply hate the physical existence of their body)
Either way, I don't see the point in trying to be politically correct about what I call myself, or how other scientists try to classify me. My condition is an oddity, a trait is a trait, and classifying those traits is what biological sciences are all about. I think science is awesome, so more of that please. :)
Think of the honey bee. Most of the individuals in the hive will never reproduce but they all contribute to the survival of the genes they share in common.
Humans in a family are not all identical like worker bees but the principle of gene conservation and propagation is the same.
And another example of an eusocial species would be the naked mole rat. In the end I think it should be more than fair to say that we are past the point of needing to pass on our genes absolutely, particularly because we're already straining Earth's resources without further encouraging reproduction.
There are many genes that are expressed naturally, or through mutation, that would remove from reproductive ability.
Kind of throws a spanner in you lack of logic... Do you think this inability to reach a valid conclusion based on a set of inputs is a choice or genetic?
The point of the now almost flagged comment I was replying to (quoted above to make it easier to follow) is that being unable to reproduce is proof that the condition is not genetic. Whether it's one gene or a collection, that they are rare or common, that we know the mechanism in detail or not, becomes irrelevant in this context.
The inability to reproduce "proves" only that you are unable to reproduce. There is no conclusion that one can draw from this regarding the cause: genetic mutation, accident, etc. Unless you (or the serial downvoters who most likely didn't bother to understand what I said) can prove the connection implied by the poster above, I see no argument to contradict my statement.
See also: "MLK was a criminal and therefore was bad/should be locked up", "Taxation is theft and therefore bad", etc etc
What if homosexuality is a naturally occurring trait that arises more frequently in the presence of environmental pollutants (say endocrine disruptors or whatever causes allergies)?
This is not implausible; in fact I’d be surprised if it weren’t probable (that enviromental pollutants affect human brain development and therefore sexuality)
What are the consequences or the course of action -if any - that should be taken?
I have come across this before when I was a biologist many years ago. Homosexuality does not look like a genetic trait. It looks remarkably like a disease state - even an infectious one at that. But the first and last time I discussed this with other biology students, the reaction was very bad.
Research like this may get interpreted politically, and therefore ignored or even suppressed and the researchers lose credibility.
I do not know what you would interpret as natural, but homosexuality is detrimental for the persistence of a species. It is entirely a dead-end. The correct action to be taken is to prevent and/or counter the agent that causes this.
How do you state this with such confidence? In an overpopulated world, homosexuality may be beneficial for the survival of our species. Homosexuals who do not reproduce potentially provide nanny-power to family units, or parenting power to orphans. It is in no way clear cut that "the correct action to be taken is to prevent and/or counter the agent that causes this." This is crazy talk.