By the way, MsHarmony, my previous post was not directed at you in any way. Regarding you posts, I somewhat agree, and i think we don't yet know the full degree to which genetic does (and does not) influence these kinds of choices. But even if we find a certain behavior is tied strongly to our genetic makeup, then... (insert previous post here).

We are simul-posting...

My follow-up post was made before I read this. I definitely agree on the 'too much emphasis' part of what you say... even if we find genetic predilections, we still have choice in our behaviors, and many of our preferences are also influenced by life experiences.

Okay, so this is said in the context of a previous convo about sexual orientation, so I'd like to disclaim, for the audience, that: I do not think that homosexuality is wrong, and I realize that it must be as hard for a homosexual person to choose not to behave homosexually as it would be for me to choose not to behave heterosexually. And equally silly.

Why not ask "If there is such a biological _disadvantage_, why didn't homosexuality as a trait die out long,long ago?"

The answer my lie in the fact that homosexuals, because they don't have to expend the time and energy to procreate and nurture their own children, confer upon the societies that accept them many intellectual gifts that advance the species. And thus, the survivablity of those of the species that _do_ procreate.

There's also the 'super uncle' theory, where gay men who don't have children provide a definite advantage to their next of kin by giving of their time and money to their brother's and sister's offspring.

Also, the genes thought to be responsible for homosexuality are carried on the X chromosone and some of those same genes in females are called 'fecundity' genes. In females, they make their owners more attractive and more fertile. This might help to explain why those genes get passed on indirectly and in such abundance.

-Kerry O.

It is apparent that homosexuality does not have one particular "cause." It is not purely genetic in origin, for instance, because the very twin studies that some interpreted as "proving" a purely genetic origin of homosexuality actually "disproved" it, because only 52% of identical twins of homosexual persons were also homosexual. If homosexuality were dependent on a particular "gay gene," both twins should have possess that gene, and thus there should have been a 100% correspondence.

A person finds him/herself with a homosexual orientation as a result of the interplay of several factors, including heredity, prenatal influence (a controversial subject, but with not only animal studies but some human studies to back it up), and environmental factors such as childhood trauma or being brought up and conditioned as a member of the opposite sex. The latter is the background of a significant number of lesbians, for instance. (in other words, Nature & Nurture).
*** "Homosexuality & heterosexuality are likely to be the result of an interaction of several different factors, including genetics, hormonal & environmental factors. ***
While there seems to be strong evidence to point to a biological link to a homosexual orientation, it is also very likely that, for some people, a homosexual orientation develops as a result of psycho-sociological factors. In other words, for some, homosexual orientation may be altogether environmentally caused.

*** Studies show that genes play a significant role in determining homosexual orientation. Also, studies consistently show that male homosexual orientation is mainly (perhaps entirely) determined at conception by a person's genes. In fact, brain scans have provided the most compelling evidence yet that being gay or straight is a biologically fixed trait."

Other studies used neural magnetic resonance imaging (MRI) on a group composed of both heterosexual and homosexual men and women. They found key similarities between the brains of:
Gay males and heterosexual females, and
Lesbians and heterosexual males.

That is, homosexual and heterosexual orientation seem to be linked to pre-birth brain structures, and are not caused by factors after birth, including parenting styles, sexual molestation during childhood, or a choice by the individual.

In a subsequent experiment, the researchers concentrated on the amygdala (medical name: corpus amygdaloideum). This is a structure in the lower part of the brain that directs the individual's response to emotional stimuli. It is located at the center of the brain -- roughly halfway between one's eyeballs and the back of the head, and about halfway between the neck and the top of the head. It is active when danger is present and the person has to decide between "fight or flight." It is also active when sizing up a potential love interest or mate, and in many other emotional situations.
The studies used PET scans to measure blood flow to the amygdala. Results demostrated, again, that heterosexual men and lesbians shared a similarity: they had more nerve connections on the right side of the amygdala than on the left. Meanwhile, gay males and heterosexual women had more neural connections on the left side of the amygdala than on the right. That might be anticipated, because straight men and lesbians are both sexually attracted to women, while straight women and gay males are both sexually attracted to men.

So in fact there's a (genetic) predisposition.

The problem with this is that there was no baseline with which to compare the results. In the paper, the Karolinska team says that the brain continues to mature after puberty, especially in boys, which means that social and/or environmental factors may influence it.

How can it be decided then if the person’s brain changed due to their behavior or if their behavior was caused by the change in the brain without such a baseline? In other words, was the homosexuality caused by the difference in brain size and neural connections or were these differences caused by the homosexuality?

Dr. Whitehead said, "The brain, even as an adult, changes in response to experience. Thus, it was shown in an article published in Nature a few years ago, that a 3-month training in juggling produced measurable micro-structural changes in adult brains, and this could also be reversed."

"In other words, there is definite evidence that experience changes the structure and function of the brain."

Dr. Mamdouh El-Adl, a consultant psychiatrist in the U.K,with a special interest in psychosexual disorders, agrees. "The [study] findings do not put anyone in a position to conclude that these observed differences are unlikely to be directly affected by learned patterns and behavior," he told IOL.

"In my opinion, for drawing such a conclusion, there is a need to follow up a cohort of subjects since birth, expose them to the same environmental factors, and conduct the appropriate serial tests."

Whitehead said that the argument (i.e. that people are born with either SSA-type or OSA-type brains that do not change regardless of subsequent life experiences) is a very hypothetical one.

"Proving this would require doing brain scans on many thousand newborns and following them for 25 years in the hope of correlating birth structures with later sexual activity. The theory is inherently unlikely and experimentally a nightmare."

NOT THAT IT MATTERS<, JUST ANOTHER SIDE TO THE 'STUDY'
I think we still have no way to know whether it is genetic, biological, or merely preference stemming from both nurture and nature... there are still really no definitive answers

And to do this, you'll have to have many situations kind of like the "Truman Show", though not necessarily aired on television, in which lives are a planned series of specific events so as to do the relational experience studies. I'm ag'in' it.

Don

Sure souds like Dr. Whitehead is looking for a grant for yet another study -- for 25 years!!!