Genetic Influence on Homosexuality

On July 16th, 1993 Scientists Dean Hamer, Stella Hu, Victoria L. Magnuson, Nan Hu, and Angela Pattatucci published an article in Science titled " A Linkage between DNA Markers on the X Chromosome and Male Sexual Orientation".This article concluded that because a statistically significant group of gay men all inherited the same versions of DNA markers in the Xq28 gene region of the X chromosome their homosexuality is, at least in part, genetically influenced.
Before Hamer, the most conclusive research that had been done into genetic influences on sexual orientation were by Michael Bailey, an assistant professor of psychology at Northwestern University.Bailey did a study of 110 twins in which one of the twins was known to be gay. The sexual orientation of the other twin was then determined through a questionnaire sent to him, or if that wasn't possible, by asking the brother.The results of the study were that out of 56 pairs of identical twins, 52 percent of the co-twins also were gay, but that out of 54 pairs of fraternal twins, only 22 percent of the co-twins were gay. This study, combined with the according results of a study done on gay men and their brothers in 1985 by Richard Pillard and James Weinrich, encouraged Hamer to begin his own research.
The first step in Hamer's research was to collect two groups of gay men.The first group's purpose was, like Bailey's study, to determine whether homosexuality runs in the family.These gay men were randomly selected. "Random" in this case means without the bias of being selected specifically because they were known to have gay relatives.The second group of gay men consisted of pairs of gay brothers.These subjects would be used for DNA linkage studies.
The first study, involving the randomly selected gay men, was based on pedigrees of the men's families.The sexual orientation of the relatives was determined by information from the brothers and questionairres given to the relatives.When the brothers were unsure and the relatives were not available to answer questionnaires they were marked on the pedigree as unknown.
The results of the pedigrees were as follows:

Relative Gay/Total Percent Gay

Fathers 0/76 0.0
Brothers 14/104 13.5
Maternal uncles 7/96 7.3
Paternal Uncles 2/119 1.7
Maternal cousins thru aunt 4/52 7.7
Maternal cousins thru uncle 2/51 3.9
Paternal cousins thru aunt 3/84 3.6
Paternal cousins thru uncle 3/56 5.4

Population Frequency 14/717 2.0

The fact that there is a loading of gay relatives on the mother's side suggests that the inheritance comes from a gene on the X-chromosome (Men receive an X-chromosome from their mothers and a Y-chromosome from their fathers).Such a gene is called an X-linked gene.
It is important to state at this point that Hamer and his group were not searching for a single " gay gene" that was the sole determiner of it's carrier's sexual orientation. If this were true, and if the gene was on the X-chromosome, than the pedigree results should have shown that the brothers of gay men had a 50 percent chance of being gay, the uncles 25 percent, and the cousins 37.5 percent. Because the results of the pedigrees showed lower percentages the probability was that a gene involved was part of complex inheritance. Complex inheritance means that several genes are required to produce a trait, or that genes in combination with environment are necessary to produce a trait.
The next step in Hamer's study was DNA Linkage Analysis.DNA Linkage Analysis is based on the fact that pieces of DNA are passed on whole from one generation to the next. This means that if two genes for two different traits are located close to one another on a piece of DNA they will be inherited together. For example, if a mother fruit fly has purple eyes and a black body, and the father has red eyes and a white body, and eyes and body type are linked genes ( they are located on the same DNA molecule) their babies are limited to one of only these two combinations.Linkage Analysis can be used for two purposes; mapping genes and determining whether genes exist.The former concerns using one gene with a known placement on the chromosome as a marker to track down the placement of a linked gene so that it's place on the gene map can be ascertained.Using the example of the fruit flies this means that if the loci of the gene for body color is known but that of eye color isn't known the fact that the two are linked means the exact loci of eye color can be found in the same chromosomal region as body color.The latter, determining whether a gene exists or not, was Hamer's primary concern.Linkage Analysis is used for this because if a trait is influenced by a gene than people who share the trait should share a piece of DNA close to the gene.This means that Hamer's gay brothers should share the same markers in a specific gene region on the X-chromosome.
Even if the gay brothers are found to have common markers in a gene region it does not mean that that gene region is definitely linked to their sexual orientation. Whether that is true or not is determined by the LOD score of the linkage study. LOD stands for logarithm of the odds ratio. The odds ratio is equal to the probability of the observed data assuming linkage, divided by the probability of the same data without linkage.To keep the numbers manageable, the sum is converted into the logarithm to the base 10.Thus an LOD score of 3 means there is only a one-in-one-thousand chance the linkage is caused by accident and not actually linked to the particular trait all of the subjects share. Most geneticists agree that an LOD score of 3 means a significant linkage between a marker and a trait.
DNA is determined to have the same markers by the following process: DNA from each person is divided into plastic trays. In each well that holds DNA there is also primers, enzymes, and radioactive material that makes the DNA visible. Each tray is put into an oven that causes the segments of DNA to multiply. Separately a substance like gelatin is poured into the paper-thin space between two sheets of glass. The liquid hardens into gel divided by thin lanes and each DNA sample is placed in a separate lane. Current is applied to the gel casing molecules to move toward the positive charge. After several hours one glass sheet is removed and a piece of X-ray film covers the exposed gel and picks up images of the radioactive molecules. The molecules, frozen at different points towards the positive charge, leave small dark bands on the film. If a pair of brothers share the same pattern of bands, this means they share the same marker.
The first marker Hamer tested was DXS52, simply because its products can be seen without using the complicated process that involves radioactivity. He found that when searching the DNA of four pairs of brothers for this marker all came up concordant, and that when examining the DNA of the four mothers three of them had different forms of the marker on their two X chromosomes.If the mothers had had the same version of the marker on each X-chromosome it wouldn't have meant anything that the brothers shared the marker because it would have been the only option. The fact that they could have inherited the other version but didn't suggested that there could be a linkage between that marker and their sexual orientation.The gene region of this marker was Xq28. Xq28 is a region that holds the genes that can cause color blindness and hemophilia. Because these two disorders are well studied there are many known markers in Xq28.This meant that there were a lot of other markers, besides DXS52, to look for in the gay brothers' DNA. If a high percentage of the gay brothers shared many of these markers in Xq28, a high enough percentage and with enough markers to achieve an LOD score of 3, than it could be concluded that there was a genetic influence on the sexual orientation of these studied men.This is in fact what happened. Hamer had been phenomenally lucky with the choice of DXS52 as his initial marker, and with the decision to examine more markers in Xq28.
Two of the markers in Xq28 that were found to be concordant in gay brothers were discovered to be part of a curious genetic event that seems plausibly linked to homosexuality. Research by Diha Freije and Helen Donis-Keller showed that these two markers are at the tip of the long arm of the X-chromosome, which marks the end of the Xq28 region. This ending section is identical to the corresponding section of the Y-chromosome.Every once in awhile-in about 2 percent of male meioses-the X and Y chromosomes get jumbled up, and this little strip of DNA from a Y chromosome is "mistakenly" passed to a daughter (or a bit of the X goes to a son). That means boys are getting a tiny bit of a "female" chromosome and girls are getting a bit of a "male" chromosome.

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There have been many studies on gender non conformity in lesbians and gay men. These studies include retrospective surveys with homosexuals and heterosexuals about their childhood. In a recent compilation of forty-one studies, Michael Bailey ( of Northwestern University) and Kenneth Zucker ( of the Clarke Institute of Psychiatry in Toronto) found that lesbians and gay men were significantly more gender nonconformist than heterosexuals in the following gender-differentiated traits: 1) participation in rough-and-tumble play, competitive athletics, or aggression, 2) toy and activity preference, 3) imagined roles and careers( significant difference for men only) , 4) cross-dressing, 5) preference for same-or opposite-sex playmates, 6) social reputation as " sissy" or " tomboy", and 7) gender identity. This trend of gender non conformity indicates the relevance of hormones in homosexuality.
Both male and female bodies produce the hormones estrogens and androgens. Estrogens, primarily estradiol, are more prevalent in females and responsible for development of female's secondary sex characteristics and " feminine " behavior such as maternal instincts. Androgens, primarily testosterone, are more prevalent in males and responsible development of male secondary sex characteristics and "male" behavior such as aggression.
While it is unethical to experiment with humans by injecting excesses of androgens or estrogens during fetal life to see if the children are born gay, such results are obtained through natural circumstance or human misadventure. Two such instances are; the natural genetic disorder congenital adrenal hyperplasia ( CAH) and the, presently realized as disastrous, drug called diethylstilbestrol (DES).
If a fetus is afflicted with CAH a genetic error causes the enzyme 21-hydroxylase to be defective which disrupts synthesis of hormones in the cortex of the adrenal gland. Instead of secreting corticosteroids and mineralocorticoids the gland secretes an excess of androgens. Females born with CAH are immediately treated with drugs to obtain normal hormone balances, therefore their abnormal androgen exposure is limited to fetal life and a few days postnatal life. As adults women that were afflicted with CAH are more likely than other women to experience sexual attraction to women, or to both women and men. The likely explanation for this is that if the androgens reach a certain threshold they influence the brain circuits for sexual orientation in the male-typical direction.
DES is a synthetic estrogen that pregnant women who were at risk for miscarriages were prescribed between 1940 and 1971. Since 1971 DES was discovered to cause serious side effects such as cervical and vaginal cancer in female offspring, and was banned. During gestation the fetus uses mechanisms to prohibit maternal estradiol from reaching it's brain. DES, however is not a steroid, like actual estrogens, and therefore escapes the inactivation by these mechanisms. DES binds to estrogen receptors in the fetal brain, which is a step in the organization of testosterone throughout the body. These effects normally do not take place until post natal life, so females exposed to DES have an increase in testosterone organization.
Heino Meyer-Bahlburg and Anke Ehrhardt ( of Columbia University ) have shown that DES-exposed women are significantly more likely to experience same-sex attraction than their unexposed sisters or other comparison groups.

Richard Pillard's MIH theory

Presently the most complete theory on how a gay gene might work is the Mullerian Inhibiting Hormone theory proposed by Richard Pillard of Boston University. MIH is a hormone used in sexual differentiation of the fetus. Up until the third trimester all fetusus have identical packages of both female and male interior sexual equipment. The Wolffian duct is the male equipment and the Mullerian duct is the female equipment. These ducts are tubes of tissue that lie behind the bladder. Next to them is an undifferentiated sex gland and an indistuinguishable genital tubercle.
If the fetus is a girl and has two X chromosomes the Mullerian duct will develop into internal female sex organs. The Wolffian duct which recieves no testosterone shrivels up and stays functionless on top of the ovaries.
If the fetus is a boy the process is more complicated. A boy has an X and a Y chromosome, and on the tip of the Y chromosome is a gene called TDF-testis determining factor. TDF causes the secretion of testosterone that develops the testes and penis. TDF also causes the secretion of Mullerian Inhibiting Hormone that kills off the Mullerian duct. The testosterone is masculinizing and the MIH is defeminizing.
Pillard hypothesizes that MIH is also involved in defeminizing the brain.It is known that rat's brains are sexually differentiated by testosterone. Patricia K. Donahoe, chief of Pediatric Surgery at Massachusetts General, has been able to raise antibodies to MIH in the spinal cord and brain of the rat. If it is true that MIH works also to defeminize the brain than maybe a gay man's brain had complications in this step. The MIH could defeminize the man's actual Mullerian duct, but a gene could cause it too be dysfunctional in defeminizing the brain. It could be dysfunctional because the hormone never reaches the brain, or perhaps the receptors on the brain for the hormone are defective. Either way, the result is a masculine body but with a partially feminine brain. This is concordant with LeVay's observations of gay men having in some areas, essentially women's brains.
For lesbians this theory would mean that they have a gene that somehow triggers the production of MIH that is only effective on the brain. Their result would be a feminine body with a partially masculinized brain.
A phenomenon that supports this theory is the in utero death rate of males. For every 100 females conceived, there are approximately 130 male conceptions, a huge imbalance in favor of boys. At birth, however, the sex ratio is virtually identical at 1.02 females to 1.04 males. This is because for the fetus to become male it has to go through a much more elaborate process than to become female. Going through the complications with MIH and testosterone means potential for things to go wrong and the fetus to die. This could explain why there are approximately two gay men for every gay woman. The male's heterosexuality is more vulnerable to complications than the female's heterosexuality. Also many potential lesbians die in utero because they go through the male MIH process which is prone to complications and death.

RaneStarr said:

Honey, I'm not talking about a few loose hairs. Her whole face was full of beard hair, including the mustache. I'm 32 and EVEN I cannot grow hair like she could! No joke.

Ice, don't even bother using science to back you up. Scientists aren't God and God says homosexuality is a sin!!!

Thanks for the info, you rock!

ice, like eye said b4... knockurselfout, trying 2 knock the word of God... truth will prevail...

"Give 2 Caesar what is of Caesars, and give what is of God what is of God " - Jesus Christ

That is what Jesus responded when unbelievers were trying to trick him into puting his foot in his mouth regarding paying taxes to Caesar (wether they should pay or not)

Therefore, eye say the same 2 u ICE... give 2 scientists what is of science and give 2 God what is his... in the end we will find out who is right, Human Hypothesis' or the creator of Earth and beyond

RaneStarr said:

At this point, I will be disrespectful and say fuck god.

SupaFunkyOrgangrinderSexy said:

well maybe she was on hormones 2 become a man? or maybe she had a hormonal dysfunction... what is the big deal? a mustache does not make her abnormal and having one is not a sin...
maybe culturally speaking it is not okay for us in today's age 2 have a mustache... that does not mean women can'thave a mustache... 200 years ago women wearing pants was considered incorrect (socially speaking) those are cultural things not moral things.

ICE, u and Richard Pillard (the guy u just posted the article from) can xplain 2 god in more detail when u meet him face2face how ur right and God is wrong

eye'm sure he will find u and Richie very amusing

RaneStarr said:

I've said it before and I'll say it again:

I have no use for dogmatic religious zealots. Do you also believe in the fucking tooth fairy?

RaneStarr said:

Surely they won't get past St Peter! being gay and all.

don't worry guys, i'll smack the wanker for ya!

y'here me God? you tubby bitch.

Thecherryloon said:

Well, I'm not gay, but I still won't be going to heaven, as there is no such thing.

IceNine said:

How do you know that there is no heaven? Have you died before?

AbucahX said:

I have not died before, but there is no good reason to believe that there is a mystical place of happiness and bliss where we all go when we die. In my opinion, that is just silly.

I don't mind other people believing in it and you are always very cool, so please don't take my comments the wrong way. You are all cool with me and I respect you.

Now... heavy-handed fuckheads who spew dogma and continue to tell everyone exactly how wrong they are and how right the bible is annoy the fucking fuck out of me. I can think of a few of these fucking fucks who are fucking annoying the fuck out of me with their fucking dogmatic bunch of fucking shit.

IceNine said:

LOL, Icenine, i'm not taking your words the wrong way dude. I'm just messing with ya, thats all.

RaneStarr said:

well maybe she was on hormones 2 become a man? or maybe she had a hormonal dysfunction... what is the big deal? a mustache does not make her abnormal and having one is not a sin...
maybe culturally speaking it is not okay for us in today's age 2 have a mustache... that does not mean women can'thave a mustache... 200 years ago women wearing pants was considered incorrect (socially speaking) those are cultural things not moral things.[/quote]

She was not on hormones. That was the natural state of her body. My point is, how are you going to call her a sinner when the possibility exists that she cannot help the way she feels or is? Try as you might, without science, you can't regulate your hormones and if she was born that way who are Christians to say that she is going to hell?

I wouldn't want to go to heaven if it meant spending eternity with all those wishy washy God botherer type people.

Hell is nice and warm, and full of interesting characters as far as i can tell.

on a side note where does a satanic, S&M type person goes when he dies.If God punishes him with hell, surely he'll arrive with a hard on?

SupaFunkyOrgangrinderSexy said:

She was not on hormones. That was the natural state of her body. My point is, how are you going to call her a sinner when the possibility exists that she cannot help the way she feels or is? Try as you might, without science, you can't regulate your hormones and if she was born that way who are Christians to say that she is going to hell?[/quote]

Shouldn't they question God for fucking up?

IceNine said:

Hmm... sounds familiar!

Natsume said:

Are you trying to tell me that you have seen people do that on here?

:LOL:

4 all the lurkers out there,

look at the atheists and there choice of words "fuck this" fuck god, fuck that, fuck, fuck, fuck

such hostility 2 someone they say never xisted LOL
Jesus never did harm 2 anyone and yet such hatred is in this thread for him... why is that? because the demons within them can't take hearing the truth, they hate the honesty and integrity of the word of God

all of u put 2gether can't take me and my Jesus on!

RaneStarr said:

Ooooh, that is really deep of you!

My advice to you is this:

Check into a mental hospital immediately... do not wait until morning... drive fast and do not stop for red lights. There is something very wrong with you.

:LOL:

RaneStarr said:

Your Jesus couldn't even take care of himself...

In case you forgot some people nailed him up to some wood.

:LOL:

IceNine said:

Oh no, of COURSE not!

Silly ice!

RaneStarr said:

The negative vibes on this thread are less directed at Jesus, but more aimed towards you and your ideas.

It's a simple observation, not an opinion on my behalf. Just thought I'd point that out...

Natsume said:

You are right, Natsume!

I would have preferred if RaneStarr would have been the one nailed to some wood.

*just kidding, RS... nobody deserves to be nailed to wood... not even braindead zealots

IceNine said:

:tsk: :tsk: ur sins could not b 4given if he didn't U LUCKY BOY U! cuz if u decide 2 repent 10 years 4rom now all this that u r saying will b erased 4rom memory... isn't god grand??

RaneStarr said:

Onward Christian Soldier!

Actually, you do Jesus a tremendous disservice in the way you present yourself as knowing exactly what He and God meant. You don't know. Trust God enough to deal with it in His way, not yours.

Stupid cunt!

RaneStarr said:

Fuck repenting
Fuck all that silly bullshit
Fuck, fuckity, fuck, fuck, fuck
Fuck Princebonics
Fuck Prince
I am a lucky boy in that I don't believe in stupid, pointless dogma and imaginary big brother figures.

NegaTIVity said:

Not to be positive here, NegaTIVity, but you are so very right... this dunce is making baby Jesus cry with her blindly dogmatic bullshit.

Zealots can suck the ass of a dead monkey.

Natsume said:

really what r my - vibes? lol... eye never insulted anyone, all eye've said is how Jesus is 4giving, loves, forgives... eye never said anything negative about being gay or being straight ... the only thing eye'm being convicted of is of being + about Jesus! meanwhile all of u r nailing me 2 the cross, calling me a cunt, saying fuck god, bla bla bla ...

u guys r so funny... JESUS LOVES ALL OF U! but eye don't cuz y'all r mean! and eye don't 4give!

IceNine said:

Hey now, I don't think POOK would appreciate that kind of language!