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View Full Version : Homosexuality: It's In Your Genes



Tryggvi
Monday, March 8th, 2004, 07:48 PM
Part I
Mitch King
Charlottesville, VA

WASHINGTON, 93 Jul 16 --A group of researchers from the National Institutes of Health have discovered statistical evidence that one form of male homosexuality is genetically transmitted from mothers to their sons through the X chromosome. The study involved pedigree and DNA linkage analyses on 114 families of homosexual men.

Subjects included 76 self-acknowledged homosexual men and their relatives over age 18 recruited through a Washington DC HIV clinic and local homophile organizations, and 38 pairs of homosexual brothers and their relatives recruited through advertisements in local and national homophile publications. Participants were white non-Hispanic (92%), African American (4%), Hispanic (3%), and Asian (1%). Sexual orientation was assessed by the Kinsey scales, and subjects rated themselves on four aspects of their sexuality: self-identification, attraction, fantasy, and behavior. Most of the men (average age 36) reported experiencing their first same-sex attraction by age 10, which was prior to the average age of puberty (age 12).

For the first sample, (the 76 men from the Washington DC area), D. H. Hamer, S. Hu, V. L. Magnuson, N. Hu, and A. M. L. Pattatucci found that 13.5% of the brothers, 7.3% of the maternal uncles, and 7.7% of the sons of maternal aunts of homosexual men were self-acknowledged homosexuals--compared to the background rate of 2% which was an estimate obtained from 717 randomly selected males who were the subjects of previous research. Other significant findings were that 5.4% of the sisters of homosexual men were self-acknowledged lesbians (versus a 1% background rate), and 4.7% of the of the brothers of lesbians were self-acknowledged homosexuals (versus a 2% background rate). Homosexuality among fathers and all other types of paternally related relatives of the homosexual subjects was not significantly greater than the background rate.

Although higher than the background rates, the observed rates of homosexuality in the maternally derived uncles and male cousins of gay men in the first sample were lower than would be expected for a simple Mendelian trait, so the researchers hypothesized that there might be at least two types of male homosexuality--one which was male-limited and maternally inherited versus one which was sporadic, not sex-limited, or not maternally transmitted. To test this hypothesis, Hamer et al. recruited the second sample--the 38 families in which there were two homosexual brothers.

If their hypothesis concerning the existence of two types of homosexuality was correct, one would expect to see higher rates of male homosexuality in the maternally derived relatives of the second sample than in the first, and indeed, this is what was observed: 10.3% of the maternal uncles and 12.9% of the sons of maternal aunts of the homosexual brothers were, themselves, self-acknowledged homosexuals. Rates of homosexuality among the paternally derived male relatives were unchanged, or decreased compared to the first sample.

For the linkage analysis, DNA from 40 pairs of homosexual brothers (38 from the sib- pair pedigree study, and 2 from the random sample) and from their available mothers and siblings was studied and typed for a series of 22 markers that span the X chromosome. A significant linkage between homosexual orientation and markers in a region of the X chromosome known as Xq28 was detected--33 sib-pairs (82.5%) had inherited the same genetic information at all five markers within this region, whereas 7 pairs (17.5%) showed differences at one or more markers. The probability that such coinheritance could occur by chance alone is much less than 1.0%. As the research report states, "it appears that Xq28 contains a gene that contributes to homosexual orientation in males".

The 7 pairs (17.5%) of homosexual brothers who did not coinherit all of the Xq28 markers suggest that other factors, including nongenetic ones, play a role in determining sexual orientation. There was no significant evidence for linkage between sexual orientation and markers lying outside of Xq28, however, the researchers acknowledge that a much larger sample would be required to stringently eliminate all other regions from playing a role in sexual development in a small proportion of families.

Reference: Hamer, D. H., Hu, S., Magnuson, V. L., Hu, N., and Pattatucci, A. M. L. "A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation", Science, Vol 261, 321-327, 16 Jul 93. Science is published weekly by the American Association for the Advancement of Science, Washington, DC.

Unrestricted reproduction or electronic transmission is authorized when due credit is given to the author.


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Part II
Mitch King
Charlottesville, VA

WASHINGTON, 94 Dec--Two Canadian researchers have discovered a statistical relationship between the number of ridges on men's fingertips and homosexuality, contributing additional evidence to the theory that sexual orientation can be influenced by biological events that occur at conception or early in fetal life. Specifically, J. A. Y. Hall and D. Kimura of the University of Western Ontario examined the fingerprints of 66 homosexual and 182 heterosexual men, comparing the number of ridges on the index finger and thumb of the left hand with the number of ridges on the index finger and thumb of the right hand.

If the number of ridges on the index finger and thumb of the left hand exceeds the number of ridges on the index finger and thumb of the right hand, one's fingerprints are said to exhibit leftward directional asymmetry. Hall and Kimura found such leftward directional asymmetry in the fingerprints of 30% of their homosexual subjects versus 14% of their heterosexuals.

Sexual orientation was measured by having all subjects rank themselves, in terms of fantasy and experience, via the Kinsey scale.

The number of ridges on the fingertips is largely determined at the moment of conception by genetics, subject to modification by local environmental factors (local hormone levels, etc.) up to the 16th week of fetal life. Only extensive mechanical damage alters the number of ridges after this time. According to Hall and Kimura, a significant statistical correlation between a prenatally determined characteristic such as one's fingerprints and an adult behavioral trait such as one's sexual orientation is consistent with previous research suggesting an early biological contribution to adult sexual orientation.


Reference: Hall, J. A. Y. and Kimura, D. "Dermatoglyphic Asymmetry and Sexual Orientation in Men", Behavioral Neuroscience, Vol. 108, No. 6, 1203-1206, Dec 94. Behavioral Neuroscience
is published bimonthly by the American Psychological Association, Washington, DC.

Unrestricted reproduction or electronic transmission is authorized when due credit is given to the author.

Gladstone
Monday, March 8th, 2004, 11:34 PM
I think the genetic thing would explain homosexuality with many men (though not all); it would also explain the phenomena of gays stating it is a miserable "lifestyle" that no one would freely choose. Will PC allow for science to attempt a means to correct these genes in vitro? We'll see.

cosmocreator
Tuesday, March 9th, 2004, 09:18 AM
It could only be in the genes if it is a mutation from the parents obviously. If it were genetic, everyone would be gay and humans would stop reproducing. I think it is bogus and they are trying to justify homosexuality by squewing science. Homosexuality is a mental illness.

Louky
Tuesday, March 9th, 2004, 05:44 PM
A group of researchers from the National Institutes of Health have discovered statistical evidence that one form of male homosexuality is genetically transmitted from mothers to their sons through the X chromosome. The study involved pedigree and DNA linkage analyses on 114 families of homosexual men.
How many "forms" of male homosexuality are there?

Glenlivet
Tuesday, March 9th, 2004, 06:30 PM
What do you think about the social aspect where there's been no male role model around the boy?



It could only be in the genes if it is a mutation from the parents obviously. If it were genetic, everyone would be gay and humans would stop reproducing. I think it is bogus and they are trying to justify homosexuality by squewing science. Homosexuality is a mental illness.

Timo
Tuesday, March 9th, 2004, 10:55 PM
Homosexuality is a mental illness.
I agree, though even mental illnesses can be passed down genetically.
If the effects happen at birth and can't be changed, as the homosexuals claim, that is the best argument for complete eradication of their kind.

Scoob
Wednesday, March 10th, 2004, 12:27 AM
I have a pet theory, which is semi-mystical. I believe that every race or people has a sort of group-will that binds them together, almost like a collective self - like there is a "human self" that transcends the needs of each cell, and regulates things as an overall system. Part of the group-will preserves itself with the sex drive, and also drive to hold family together - in other words to hold its form. When this "force field" is disrupted, you find families in chaos, non-procreative sexual practices, low birth rates, and a general lack of direction, group-pride, etc. This is how I think of these things. It sounds mystical, unless Will or bio-electricity really exists at some group level, as I believe it does (much like the Chinese idea of "Chi").

On a more down-to-earth, scientific level: I wonder if there could be some sort of stress-related hormones at work when populations are too high, that generates kids who have homosexual tendencies.

I would be very interested in a real human-species study on homosexual behavior, and what kinds of situations correlate to it: overcrowding, chemicals in environment (could include pheremones from other races!), etc. Until then, everything we say is hot air.

cosmocreator
Wednesday, March 10th, 2004, 06:42 AM
I think crowding may play a role in homosexuality. Others have said that Europe has the most homos. I disagree. I think the Far East does, India, China, SE Asia. I think it is least common in wide open spaces like rural Canada. I think large cities are a cause of and refuge for mental illness in general.

old aryan
Wednesday, March 10th, 2004, 06:46 AM
I think crowding may play a role in homosexuality. Others have said that Europe has the most homos. I disagree. I think the Far East does, India, China, SE Asia. I think it is least common in wide open spaces like rural Canada. I think large cities are a cause of and refuge for mental illness in general.
I agree with you. It seems to be a mental illness, possibly from genetic abnormalities, that is pushed to the forefront in overcrowded conditions. I do not believe that humans were meant to live in crowded and cramped conditions. And I do not believe that illness should be legitimized as acceptable normal lifestyles just because it is PC.:(

cosmocreator
Wednesday, March 10th, 2004, 06:54 AM
I agree with you. It seems to be a mental illness, possibly from genetic abnormalities, that is pushed to the forefront in overcrowded conditions. I do not believe that humans were meant to live in crowded and cramped conditions. And I do not believe that illness should be legitimized as acceptable normal lifestyles just because it is PC.:(

Different races and even subraces can tolerate crowding better than others. I think Mongoloids and Mediterraneans are more tolerant than Upper Paleolithics which seem to like wide open spaces.

Glenlivet
Wednesday, March 10th, 2004, 09:28 AM
Almost all Northern Europeans are used to live with fewer people. There are no Metropolises in the north. Germanic tribes lived in small village communities. They were semi-nomadic farmers and herders.



Different races and even subraces can tolerate crowding better than others. I think Mongoloids and Mediterraneans are more tolerant than Upper Paleolithics which seem to like wide open spaces.

Zyklop
Saturday, March 4th, 2006, 05:11 PM
http://images.livescience.com/template_images/livescience/transpacer.gif Mom's Genetics Could Produce Gay Sons
The arrangement of a mother's genes could affect the sexual orientation of her son, according to a new study. The finding, detailed in the February issue of the journal Human Genetics, adds fuel to the decade-long debate about whether so-called "gay genes" might exist.

The researchers examined a phenomenon called "X chromosome inactivation" in 97 mothers of gay sons and 103 mothers whose sons were not gay.


X and Y

Chromosomes are large thread-like molecules that contain an organism's genetic instructions. Humans have 23 chromosome pairs. The X chromosome (http://forums.skadi.net/redirector.php?url=http%3A%2F%2Fwww.live science.com%2Fhumanbiology%2Fap_050316_c hromosomes.html) is one of two sex chromosomes in mammals; the other is the Y chromosome (http://forums.skadi.net/redirector.php?url=http%3A%2F%2Fwww.live science.com%2Fhumanbiology%2F050901_ap_y _chromosome.html). Females have two X chromosomes and no Y's, while males have one X and one Y.

Even though women have two X chromosomes, only one is functional because the other is inactivated through a process called "methylation." "It gets wrapped up in a ball and is not used with the exception of a few genes," explained study leader Sven Bocklandt of the University of California, Los Angeles.
If one of the females' X chromosomes is not turned off, then there is too much genetic material, which can lead to a harmful overabundance of proteins. Down syndrome, for example, results from the presence of an extra copy of chromosome 21.

Big difference

Normally, X chromosome inactivation occurs at random: half of the cells in a woman's body will have one X chromosome inactivated, while the other half inactivates the other chromosome.

However, when the researchers in the current study examined cells from the 42 mothers who had at least two gay sons, they found that about a quarter of the women in this group showed something different.

"Every single cell that we looked at in these women inactivated the same X chromosome," Bocklandt told LiveScience. "That's highly unusual."

In contrast, only 4 percent of mothers with no gay sons and 13 percent of those with just one gay son showed this type of extreme skewing. Bocklandt thinks this suggest that a mother's X chromosomes partly influences whether her son is gay or not.

"We think that there are one or more genes on the X chromosome that have an effect on the sexual orientation of the sons of these mothers, as well as an effect on the cells we were looking at," Bocklandt said.


Other chromosomes implicated

Bocklandt was also involved in an earlier study that looked at the entire human genome of men who had two or more gay brothers. The researchers found identical stretches of DNA on three chromosomes—7, 8 and 10—that were shared by about 60 percent of the gay brothers in the study.

That study also found mothers to have an unusually large role in their son's sexual orientation: the region on chromosome 10 correlated with homosexuality only if it was inherited from the mother.

The results from these two studies suggest that there are multiple genetic factors involved in determining a person's sexual orientation and that it might vary depending on the person.

"We think that there are going to be some gay men who are X chromosome gay men and some who are chromosome 7 gay men or chromosome 10 gay men or some combination," Bocklandt said in a telephone interview.

Most researchers now think that there is no single gay gene that controls whether a person is homosexual or not. Rather, it's the influence of multiple genes, combined with environmental influences, which ultimately determine whether a person is gay.


A touchy subject

Research into the genetics of sexual orientation is controversial. Religious leaders who believe that sexual orientation is a choice argue that such research is an attempt to legitimize homosexuality; others worry that a detailed knowledge of the genetics underlying homosexuality will open the door to genetic engineering that prevents it. But Bocklandt doesn't think these concerns should prevent scientists from asking the basic question of whether homosexuality has an underlying genetic component to it or not.

"I have no doubt that at some point we'll be able to manipulate all sorts of aspects of our personality and physical appearance," Bocklandt said. "I think if there's ever a time when we can make these changes for sexual orientation, then we will also be able to do it for intelligence or musical skills or certain physical characteristics—but whether or not these things are allowed to happen is something that society as a whole has to decide. It's not a scientific question."

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