There is actually quite a large scientific literature on genetic factors influencing homosexuality. A recent Italian paper and review (abstracts below) have shed light on why selection has not removed factors influencing homosexuality and apparently resolved this "Darwinian paradox".
The scientific debate now apparently centres on increased female fertility in women related to homosexual men through the maternal line but not the paternal line. This is classic sex-linkage, i.e. sex chromosome involvement and this study shows the genes predisposing to homosexuality, in men at least, must be X-linked. If you ever need info on medicine, here is the best search engine and I searched with homosexuality genetics : http://www.ncbi.nlm.nih.gov/pubmed/
PLoS ONE. 2008
Sexually antagonistic selection in human male homosexuality.
Camperio Ciani A, Cermelli P, Zanzotto G.
Dipartimento di Psicologia Generale, Università di Padova, Padova, Italy.
Several lines of evidence indicate the existence of genetic factors influencing male homosexuality and bisexuality. In spite of its relatively low frequency, the stable permanence in all human populations of this apparently detrimental trait constitutes a puzzling 'Darwinian paradox'. Furthermore, several studies have pointed out relevant asymmetries in the distribution of both male homosexuality and of female fecundity in the parental lines of homosexual vs. heterosexual males. A number of hypotheses have attempted to give an evolutionary explanation for the long-standing persistence of this trait, and for its asymmetric distribution in family lines; however a satisfactory understanding of the population genetics of male homosexuality is lacking at present. We perform a systematic mathematical analysis of the propagation and equilibrium of the putative genetic factors for male homosexuality in the population, based on the selection equation for one or two diallelic loci and Bayesian statistics for pedigree investigation. We show that only the two-locus genetic model with at least one locus on the X chromosome, and in which gene expression is sexually antagonistic (increasing female fitness but decreasing male fitness), accounts for all known empirical data. Our results help clarify the basic evolutionary dynamics of male homosexuality, establishing this as a clearly ascertained sexually antagonistic human trait.
Arch Sex Behav. 2008
New Evidence of Genetic Factors Influencing Sexual Orientation in Men: Female Fecundity Increase in the Maternal Line.
Iemmola F, Camperio Ciani A.
Department of General Psychology (LIRIPAC), University of Padova, via Belzoni 80, 35121, Padova, Italy.
There is a long-standing debate on the role of genetic factors influencing homosexuality because the presence of these factors contradicts the Darwinian prediction according to which natural selection should progressively eliminate the factors that reduce individual fecundity and fitness. Recently, however, Camperio Ciani, Corna, and Capiluppi (Proceedings of the Royal Society of London, Series B: Biological Sciences, 271, 2217-2221, 2004), comparing the family trees of homosexuals with heterosexuals, reported a significant increase in fecundity in the females related to the homosexual probands from the maternal line but not in those related from the paternal one. This suggested that genetic factors that are partly linked to the X-chromosome and that influence homosexual orientation in males are not selected against because they increase fecundity in female carriers, thus offering a solution to the Darwinian paradox and an explanation of why natural selection does not progressively eliminate homosexuals. Since then, new data have emerged suggesting not only an increase in maternal fecundity but also larger paternal family sizes for homosexuals. These results are partly conflicting and indicate the need for a replication on a wider sample with a larger geographic distribution. This study examined the family trees of 250 male probands, of which 152 were homosexuals. The results confirmed the study of Camperio Ciani et al. (2004). We observed a significant fecundity increase even in primiparous mothers, which was not evident in the previous study. No evidence of increased paternal fecundity was found; thus, our data confirmed a sexually antagonistic inheritance partly linked to the X-chromosome that promotes fecundity in females and a homosexual sexual orientation in males.
Originally posted by KazetNagorraI can find no evidence to support your statements. However, it can
Explain?
be shown that homosexual or transgender men DO have a greater
chance of having a maternal aunt.
The disparate ratio of maternal aunts to uncles in male transsexuals
and homosexual men has been hypothesised to be linked to genomic
imprinting.
(Green and Young, 2000);
http://www.helen-hill.com/pdf/xdress/familycooccurance.pdf
Regarding diodurus's post of female fecundity being a result of genetic
factors from the X-chromosome, I regard this a bit of a mix up between
cause and effect. There is no more evidence to suggest that this is
a genetic effect than it is a social one. The conflicting evidence from
paternal family size of homosexual men given in the last part of the
final paragraph of diodorus's post serves to compel this line of thought.
Why don't we simply treat sexuality like any other preference? I like vanilla ice cream more than chocolate ice cream. If we prove that 90% of the World likes chocolate ice cream better, does that make my preference anomalous? Perhaps. But who cares? Is it nature? nurture? learned? Probably some sort of combination.
The only thing that sets sexuality apart is that procreating is a basic life process and it's clearly a disorder to not be able to carry out a basic life function. However, even this isn't really dispositive. Most gay men probably CAN have sex with a woman with a little advance thought and planning and all lesbian women can have sex with men. So, they won't enjoy it as much (or at all) or so they choose not to? I don't think that makes it a disorder; just a choice based on a preference.
Originally posted by sh76(gonorrhea, infections with Chlamydia trachomatis, syphilis, herpes simplex infections, genital warts, pubic lice, scabies); enteric diseases (infections with Shigella species, Campylobacter jejuni, Entamoeba histolytica, Giardia lamblia, ["gay bowel disease"], Hepatitis A, B, C, D, and cytomegalovirus); trauma (related to and/or resulting in fecal incontinence, hemorroids, anal fissure, foreign bodies lodged in the rectum, rectosigmoid tears, allergic proctitis, penile edema, chemical sinusitis, inhaled nitrite burns, and sexual assault of the male patient); and the acquired immunodeficiency syndrome (AIDS).
Why don't we simply treat sexuality like any other preference?
Would you like a flake with that sir?>
Originally posted by Thequ1ckCan’t all these things result from homosexual OR heterosexual sex?
(gonorrhea, infections with Chlamydia trachomatis, syphilis, herpes simplex infections, genital warts, pubic lice, scabies); enteric diseases (infections with Shigella species, Campylobacter jejuni, Entamoeba histolytica, Giardia lamblia, ["gay bowel disease"], Hepatitis A, B, C, D, and cytomegalovirus); trauma (related to and/or resulting in fecal incontin ...[text shortened]... ; and the acquired immunodeficiency syndrome (AIDS).
Would you like a flake with that sir?>
-some of these things may be more likely to happen with homosexual sex than heterosexual sex (and visa versa) although that just depends on exactly how it is done and the precautions taken.
But, at least unwanted pregnancy is one bad thing that definitely is NOT more likely to occur with homosexual sex! -does this mean that we should morally object to heterosexual sex in favour of homosexual sex? (not that I think there is such thing as “moral” -I think the whole concept is irrational)
Originally posted by Andrew HamiltonAbsolutely, as cancer can arise from smoking or not smoking.
Can’t all these things result from homosexual [b]OR heterosexual sex?
-some of these things may be more likely to happen with homosexual sex than heterosexual sex (and visa versa) although that just depends on exactly how it is done and the precautions taken.
But, at least unwanted pregnancy is one bad thing that definitely is NOT more likel ...[text shortened]... sex? (not that I think there is such thing as “moral” -I think the whole concept is irrational)[/b]
You chose the wrong guy on your last question. Yes irresponsible pregnancies
should be penalised! The people concerned should be fined or castrated.
The emphasis should be on a child being brought up in a loving, stable relationship
with respect to overpopulation.
Sex, as you quite rightly pointed out in your last post, is a separate issue to parenthood.
If a gay couple desperately want a child, they will go to adoption agencies or
the sperm bank. I have absolutely no problem with gay parents raising children.
However, from what I hear, the homosexual life is a difficult one, fraught with
dangers. So wouldn't it be prudent to recognise this path as what it is instead of
making inane icecream analogies?
Which brings me onto another point. I often wonder, how much of homosexuality
is about sex and how much is about relationships. It seems to me that other than
the older and wiser queens, gay men can't get their minds off sex. Every
conversation is full of inuendo and flirting. It's dull, tiring and predictable.
If homosexuality is biological, why do partners fulfil masculiine and femine roles?
Why do lesbians try often become very masculine and gay men effeminate?
If it is not the identity of sex that is compelling towards this behaviour, then it must
be something else. Expressing individuality maybe or simply hankering for attention.
Originally posted by Thequ1ck….Yes irresponsible pregnancies
Absolutely, as cancer can arise from smoking or not smoking.
You chose the wrong guy on your last question. Yes irresponsible pregnancies
should be penalised! The people concerned should be fined or castrated.
The emphasis should be on a child being brought up in a loving, stable relationship
with respect to overpopulation.
Sex, as you q it must
be something else. Expressing individuality maybe or simply hankering for attention.
should be penalised! The people concerned should be fined or castrated.
..…
That is rather heartless response to a mistake don't you think?
Why not line them up on the wall and shoot them?
…If it is not the identity of sex that is compelling towards this behaviour, then it must
be something else. Expressing individuality maybe or simply hankering for attention.
..…
Does it matter either way?
-I mean, why would it matter WHY gays are gays?
-do you think it matters why straight people are straight?
Originally posted by Thequ1ck🙄
Absolutely, as cancer can arise from smoking or not smoking.
You chose the wrong guy on your last question. Yes irresponsible pregnancies
should be penalised! The people concerned should be fined or castrated.
The emphasis should be on a child being brought up in a loving, stable relationship
with respect to overpopulation.
Sex, as you q ...[text shortened]... it must
be something else. Expressing individuality maybe or simply hankering for attention.
Originally posted by Andrew HamiltonIt's a heartlessworld. I would rather people didn't overpopulate then anihilate
[b]….Yes irresponsible pregnancies
should be penalised! The people concerned should be fined or castrated.
..…
That is rather heartless response to a mistake don't you think?
Why not line them up on the wall and shoot them?
…If it is not the identity of sex that is compelling towards this behaviour, then it must
be something else ...[text shortened]... would it matter WHY gays are gays?
-do you think it matters why straight people are straight?
the excess but that's what happens.
Why does it matter?
I don't know, that's why we are having this debate.
Personally, unless I see some definite biological evidence, I'm going to continue
treating homosexuality as a pyschological condition.
Originally posted by Thequ1ck🙄
Absolutely, as cancer can arise from smoking or not smoking.
You chose the wrong guy on your last question. Yes irresponsible pregnancies
should be penalised! The people concerned should be fined or castrated.
The emphasis should be on a child being brought up in a loving, stable relationship
with respect to overpopulation.
Sex, as you q ...[text shortened]... it must
be something else. Expressing individuality maybe or simply hankering for attention.
Originally posted by Thequ1ck….I would rather people didn't overpopulate then annihilate
It's a heartlessworld. I would rather people didn't overpopulate then anihilate
the excess but that's what happens.
Why does it matter?
I don't know, that's why we are having this debate.
Personally, unless I see some definite biological evidence, I'm going to continue
treating homosexuality as a pyschological condition.
the excess but that's what happens.
..…
Are specifically accidental pregnancies mainly responsible for overpopulation?
Are we currently overpopulated? (-not saying that we are not -I just think this is a rather subjective judgement at the current time).
Is overpopulation the main cause of mass-killings?
Are most mass-killings caused by accidental pregnancies causing overpopulation and, if so, would the motive behind those mass-killings be to “annihilate the excess” population that specifically resulted from those accidental pregnancies?
…Personally, unless I see some definite biological evidence, I'm going to continue
treating homosexuality as a psychological condition.
..…
Of course homosexuality is a psychological condition!
Heterosexuality is a psychological condition! -I have this "psychological condition" -you almost make it sound like a disease!
There is some evidence that BOTH these psychological conditions have biological causes -there is no logical contradiction in the causes of sexuality being both psychological AND biological.
But why would it matter what the cause is anyway? -what I mean by that is, whatever the cause of a persons sexuality, what relevance could it have to the “morality” of sexuality?
-this is why I don’t understand why you think the cause of homosexuality is of relevance.
Originally posted by adam warlockThen you are indeed a selfish man.
Clever enough not to be a misinformed pompous doofus.
Andrew, apologies, I'll get back to your post this evening.
Meanwhile, here is what I consider to be a nicely written article on the subject.
http://www.theatlantic.com/doc/199706/homosexuality-biology/3