gay genetic

Genome-Wide Association Study of Male Sexual Orientation:

http://archive.is/gdhmT

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Gays have differently size brain regions:

https://www.ncbi.nlm.nih.gov/m/pubmed/1887219/

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H-Y Antigen and Homosexuality in Men

Blanchard, Klassen

1997

In men, sexual orientation correlates with the number of older brothers, each additional older brother increasing the odds of homosexuality by approximately 33%. It is hypothesized that this fraternal birth order effect reflects the progressive immunization of some mothers to Y-linked minor histocompatibility antigens (H-Y antigen) by each succeeding male fetus, and the concomitantly increasing effects of H-Y antibodies on the sexual differentiation of the brain in each succeeding male fetus. This hypothesis is consistent with a variety of evidence, including the apparent irrelevance of older sisters to the sexual orientation of later-born males, the probable involvement of H-Y antigen in the development of sex-typical traits, and the detrimental effects of immunization of female mice to H-Y antigen on the reproductive performance of subsequent male offspring.

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The biology of sexual orientation has been studied in detail in several animal model systems. In the common fruit fly Drosophila melanogaster, the complete pathway of sexual differentiation of the brain and the behaviors it controls is well established in both males and females, providing a concise model of biologically controlled courtship.[26] In mammals, a group of geneticists at the Korea Advanced Institute of Science and Technology altered the sexual preferences of female mice by removing a single gene linked to reproductive behavior. Without the gene, the mice exhibited masculine sexual behavior and attraction toward urine of other female mice. Those mice who retained the gene fucose mutarotase (FucM) were attracted to male mice.

2010

https://bmcgenet.biomedcentral.com/articles/10.1186/1471-2156-11-62

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Female relatives of male homosexuals have 1.3x as many kids:

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0051088

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Bisexual females have more teen pregnancies:

https://journalistsresource.org/studies/society/public-health/teen-pregnancy-bisexual-lesbian-heterosexual-women

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Straight males carry gay genes:

http://chaladze.com/files/publications/Chaladze2016ASB.pdf

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Significant physiological roles of ancillary penile nerves on increase in intracavernous pressure in rats: experiments using electrical stimulation of the medial preoptic area:

https://www.nature.com/articles/3900650

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Hamer 1993:

http://www.jstor.org/stable/pdf/2881563.pdf

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Hamer 1995:

http://www.nature.com/ng/journal/v11/n3/abs/ng1195-248.html?foxtrotcallback=true

doi: 10.1038/ng1195-248

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Hamer 2006:

Human sexual preference is a sexually dimorphic trait with a substantial genetic component. Linkage of male sexual orientation to markers on the X chromosome has been reported in some families. Here, we measured X chromosome inactivation ratios in 97 mothers of homosexual men and 103 age-matched control women without gay sons. The number of women with extreme skewing of X-inactivation was significantly higher in mothers of gay men (13/97=13%) compared to controls (4/103=4%) and increased in mothers with two or more gay sons (10/44=23%). Our findings support a role for the X chromosome in regulating sexual orientation in a subgroup of gay men.

Extreme skewing of X chromosome inactivation in mothers of homosexual men

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C. E. Roselli and F. Stormshak

2009

The domestic ram is used as an experimental model to study early programming of the neural mechanisms which underlie homosexuality, developing from the observation that approximately 8% of domestic rams are sexually attracted to other rams (male-oriented) when compared to the majority of rams which are female-oriented. In many species, a prominent feature of sexual differentiation is the presence of a sexually dimorphic nucleus (SDN) in the preoptic hypothalamus, which is larger in males than in females.
Roselli et al. discovered an ovine SDN (oSDN) in the preoptic hypothalamus that is smaller in male-oriented rams than in female-oriented rams, but similar in size to the oSDN of females. Neurons of the oSDN show aromatase expression which is also smaller in male-oriented rams versus female-oriented rams, suggesting that sexual orientation is neurologically hard-wired and may be influenced by hormones. However, results failed to associate the role of neural aromatase in the sexual differentiation of brain and behavior in the sheep, due to the lack of defeminization of adult sexual partner preference or oSDN volume as a result of aromatase activity in the brain of the fetuses during the critical period.

Having said this, it is more likely that oSDN morphology and homosexuality may be programmed through an androgen receptor that does not involve aromatisation. Most of the data suggests that homosexual rams, like female-oriented rams, are masculinized and defeminized with respect to mounting, receptivity, and gonadotrophin secretion, but are not defeminized for sexual partner preferences, also suggesting that such behaviors may be programmed differently. Although the exact function of the oSDN is not fully known, its volume, length, and cell number seem to correlate with sexual orientation, and a dimorphism in its volume and of cells could bias the processing cues involved in partner selection. More research is needed in order to understand the requirements and timing of the development of the oSDN and how prenatal programming effects the expression of mate choice in adulthood.

Prenatal Programming of Sexual Partner Preference: The Ram Model

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Sanders 2014:

https://www.cambridge.org/core/journals/psychological-medicine/article/genomewide-scan-demonstrates-significant-linkage-for-male-sexual-orientation/864518601436C95563EA670C5F380343

doi: 10.1017/S0033291714002451

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In the case of blood type and the Rh factor, however, interesting patterns emerged. Heterosexual males and females exhibited statistically identical frequencies of the A blood type, while gay men exhibited a relatively low inci- dence and lesbians had a relatively high incidence (p < .05). In the case of the Rh factor, unusually high proportions of homosexuals of both sexes were Rh- when compared to heterosexuals (p < .06). The findings suggest that a connec- tion may exist between sexual orientation and genes both on chromosome 9 (where blood type is determined) and on chromosome 1 (where the Rh factor is regulated).

Eye Color, Hair Color, Blood Type, and the Rhesus Factor: Exploring Possible Genetic Links to Sexual Orientation

Das S. 2007

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Identical twins are not 100% identical due to differences in womb environment:

Mechanisms for differences in monozygous twins Paul Gringras, Wai Chen, 2001

doi:10.1016/S0378-3782(01)00171-2

Another issue is the recent finding that even monozygotic twins can be different and there is a mechanism which might account for monozygotic twins being discordant for homosexuality. Gringas and Chen (2001) describe a number of mechanisms which can lead to differences between monozygotic twins, the most relevant here being chorionicity and amniocity.[13] Dichorionic twins potentially have different hormonal environments because they receive maternal blood from separate placenta, and this could result in different levels of brain masculinisation. Monoamniotic twins share a hormonal environment, but can suffer from the 'twin to twin transfusion syndrome' in which one twin is "relatively stuffed with blood and the other exsanguinated"

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Twin resemblance was moderate for the 3,826 studied monozygotic and dizygotic same-sex twin pairs. Biometric modeling revealed that, in men, genetic effects explained .34–.39 of the variance, the shared environment .00, and the individual-specific environment .61–.66 of the variance. Corresponding estimates among women were .18–.19 for genetic factors, .16–.17 for shared environmental, and 64–.66 for unique environmental factors

from:

Långström N, Rahman Q, Carlström E and Lichtenstein P (2010) Genetic and environmental effects on same‐sex sexual behavior: a population study of twins in Sweden. Archives of Sexual Behavior 39(1): 75–80.
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Bailey 1991:

http://jamanetwork.com/journals/jamapsychiatry/article-abstract/495588

doi: 10.1001/archpsyc.1991.01810360053008

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http://www.nytimes.com/1991/12/17/science/gay-men-in-twin-study.html

http://archive.is/PSmzQ

https://www.christiantoday.com/article/research.points.to.genetic.element.in.homosexuality/35856.htm

https://en.wikipedia.org/wiki/Xq28

https://www.livescience.com/2623-gays-dont-extinct.html

http://archive.is/32sQz

Scientists find DNA differences between gay men and their straight twin brothers:

http://archive.is/g3lal

A novel predictive model of sexual orientation using epigenetic markers.

Authors: T. C. Ngun [1]; W. Guo [2]; N. M. Ghahramani [3]; K. Purkayastha [1]; D. Conn [4]; F. J. Sanchez [5]; S. Bocklandt [1]; M. Zhang [2,6]; C. M. Ramirez [4]; M. Pellegrini [7]; E. Vilain [1]

http://www.nature.com/news/epigenetic-tags-linked-to-homosexuality-in-men-1.18530

http://www.tim-taylor.com/papers/twin_studies/studies.html

https://www.scientificamerican.com/article/identical-twins-genes-are-not-identical/

http://archive.is/MALR3

http://www.hawaii.edu/PCSS/biblio/articles/1961to1999/1993-homosexual-orientation-in-twins.html

https://en.wikipedia.org/wiki/Xq28

Androgen receptor gene linked to XQ28

https://en.wikipedia.org/wiki/MAGEA11

http://www.sciencemag.org/news/2014/11/study-gay-brothers-may-confirm-x-chromosome-link-homosexuality

http://archive.is/E3my1