This is something I've been pondering myself recently, the leading scientific opinion is that jomosexuality is based on biology rather than being a choice, but I still wonder. I think Nature vs Nuture comes into play. Just wondering what others thoughts are.
Having sexualities other than hetero is either itself evolutionarily advantageous in some way or it's connected to another trait of ours that is evolutionarily advantageous. If it were nurture I don't think we'd be seeing homosexuality in so many other species.
Take the example of sickle cell anemia. Why on earth does this disease continue to persist despite the fact that it harms many people? It continues to exist because the benefits outweigh the costs in terms of evolution. It turns out the people who are heterozygous for the sickle cell trait have higher tolerance to malaria.
Also we can't forget that we are social creatures. Our social bonds are more important to our survival than pure strength or intelligence. Perhaps when we still lived primarily in family groups there was something advantageous about having people with other sexualities around. Check out the Bonobos... I wonder just how similar to them we would really be if we stripped away our modern cultures and taboos.
It's also important to remember that just because one is attracted to the same sex doesn't mean they aren't capable of producing offspring. Every year I have a same sex family or two whose child is in my classroom. Sometimes it's because they adopt, invitro fertilization, from a sperm bank, from a previous hetero relationship, a surrogate and so on.
I think what is comes down to is that homosexuality, bisexuality, transexuality and so on are products of complicated intermingling genetic/evolutionary processes and certainly aren't anymore a choice than being heterosexual.
You raise an interesting question. For something to make evolutionary sense (to me at least) we must adapt and procreate to pass on genetic mutations or new talents. Homosexuality almost by definition does not allow this as a gay couple cannot reproduce. So my first thought would be No, in a strictly evolutionary viewpoint homosexuality doesn't make evolutionary sense.
However. A gay couple can of course have children via a surogate or sperm donors which allows the advancement of their genetic line. At this point we are ignoring adoption as this doesn't allow the continuation of genetics, merely family.
We should also consider the possibility that we don't need to pass on talents purely to our children. We live in an age where we can share information on an almost global scale. The vast majority of the human race has access to the internet which allows us to share huge amounts of knowlege giving an evolutionary advantage. This of course does not apply to genetic mutation, that still lies with our direct descendents.
Personally I don't think I can bring myself to lean either one way or the other on whether homosexuality makes "Evolutionary Sense" or not but one question I would certainly ask is: What harm does homosexuality do?
My answer: None at all.
If, as one of the hypotheses suggests, some of the genes are carried on the X chromosome and helped females carrying it produce more offspring then it would have an evolutionary advantage which would outweigh the guys not being as reproductive.
To me, it makes total evolutionary sense. Evolution predicts variation- homosexuality, in my opinion, is just a variation- similar to different races, skin color, etc.
There is an example in my comment directly below this one. The advantage is to female reproductivity, and the "side effect" is homosexual males. You seem a little stuck on the nurture side of the fence.
Read the plethora of links I provide below. Your position seems to be based on some belief that you somehow "know" that you are correct. Your quoting religious and hate group web sites is also rather strange. I on the other hand, can equally well claim that I am living proof that gender is not a social construct, since I know very well my own history and my own core identity. I have read an enormous amount of material on the subject and am able to provide numerous links to perr reviewed papers and article from respected sources. You fail to provide a single counterpoint to gay sheep and saying "people are creative and have the ability to develop theories to describe pretty much any situation" is neither here not there. You can't magic up peer reviewed papers and actual, physical brain differences. These are facts.
The validity of my identity hinges on no such thing. I am curious why I am as I am, but I want to know what the science actually says. Let's say it is completely a choice thing, as some groups claim. Fine. My identity stands. I get to define it, and no one else. As I said, I have actually done physics research. Peer review very quickly does away with someone trying to publish at all costs.
Kasu, nobody's identity depends on an essentialist or any other theory.
You confuse the expression of gender with the innate sense of gender. Some of the mechanisms for expression vary with culture, of course. Many other expressions of gender are common across very different cultures. But I reiterate, my core identity is not contingent on you, anyone else, or anyone else's theory. It is my own.
I don't see how you reached your conclusion that it contradicts natural selection at all. Here is an article describing how a gene on the X chromosome which led to homosexuality might confer and advantage on females who possess it: http://www.psychologytoday.com/blog/the-human-beast/200906/could-ho.... You also seem to be dismissing research studies showing brain differences, e.g http://www.pnas.org/content/105/30/10273.full .