There Is No Gay Gene

[haidut]

Very apt title, in my opinion at least. And then it comes to genetic explanations of diseases, I guess an even more apt addition would be "another one bites the dust". Recently, I posted about the complete and utter failure of the genetic hypothesis to explain depression. That indictment on the genetic link in depression was written by no other but an actual "industry insider" (read: a psychiatrist).
https://raypeatforum.com/community/threads/there-is-no-depression-gene-any-evidence-so-far-has-been-errors-fraud.29145/

Now, a study claims the same may be true of (homo)sexual orientation. According to that study, at most 25% of homosexuality may be linked to genetic "hints" and even then because of the gene-wide-associations (GWA), no specific genes, or even association/cluster of genes can be used to predict when an offspring will have homosexual orientation.

Human sexual orientation has a heritable component. - PubMed - NCBI
No ‘gay gene’: Massive study homes in on genetic basis of human sexuality

"...Nearly half a million genomes reveal five DNA markers associated with sexual behaviour — but none with the power to predict the sexuality of an individual."
"...The largest study1 to date on the genetic basis of sexuality has revealed five spots on the human genome that are linked to same-sex sexual behaviour — but none of the markers are reliable enough to predict someone’s sexuality. The findings, which are published on 29 August in Science and based on the genomes of nearly 500,000 people, shore up the results of earlier, smaller studies and confirm the suspicions of many scientists: while sexual preferences have a genetic component, no single gene has a large effect on sexual behaviours. “There is no ‘gay gene’,” says lead study author Andrea Ganna, a geneticist at the Broad Institute of MIT and Harvard in Cambridge, Massachusetts."

 

[Broken man]

Thank you for this study, I think I read something along the lines that immune system changes could influence sexuality.

 

[LeeLemonoil]

Arnold de Loof has some interesting papers out on his „Calcigender“-Hypothesis. This one is free:
Only two sex forms but multiple gender variants: How to explain? - PubMed - NCBI

Are sex and gender interchangeable terms? In classical biology, both are sometimes but not always used on an equal basis for some groups of animals. However, for our own species the Homo sapiens, they are not. A major question is why are there only two types of gametes (sperm- and egg cells), two types of sex steroids, (androgens and estrogens in vertebrates, and two types of ecdysteroids in insects), while the reproduction-related behaviour of the gamete producers displays a much greater variability than just two prominent forms, namely heterosexual males and heterosexual females? It indicates that in addition to a few sex-determining genes ( = the first pillar), other factors play a role. A second possible pillar is the still poorly understood cognitive memory system in which electrical phenomena and its association with the plasma membrane membrane-cytoskeletal complex of cells play a major role (learning, imitation and imprinting). This paper advances a third pillar, that hitherto has been almost completely ignored, namely the cellular Ca2+-homeostasis system, more specifically its sex-specific differences. Differential male-female genetics- and hormone-based Ca2+-homeostasis with effects on gender-related processes has been named Calcigender before. It will be argued that it follows from the principles of Ca2+- physiology and homeostasis that all individuals of a sexually reproducing animal population have a personalized gender behaviour. Thus, subdividing gender-behaviours in hetero-, homo-, bi-, trans- etc. which all result from a differential use of the very same basic physiological principles, is too primitive a system that may yield false sociological interpretations.

 

[LeeLemonoil]

This one, even more fundamental, unfortunately isn’t freely accessible:
The endocrine system controlling sexual reproduction in animals: Part of the evolutionary ancient but well conserved immune system? - PubMed - NCBI

Drastic changes in hormone titers, in particular of steroid hormones, are intuitively interpreted as necessary and beneficial for optimal functioning of animals. Peaks in progesterone- and estradiol titers that accompany the estrus cycle in female vertebrates as well as in ecdysteroids at each molt and during metamorphosis of holometabolous insects are prominent examples. A recent analysis of insect metamorphosis yielded the view that, in general, a sharp rise in sex steroid hormone titer signals that somewhere in the body some tissue(s) is undergoing programmed cell death/apoptosis. Increased steroid production is part of this process. Typical examples are ovarian follicle cells in female vertebrates and invertebrates and the prothoracic gland cells, the main production site of ecdysteroids in larval insects. A duality emerges: programmed cell death-apoptosis is deleterious at the cellular level, but it may yield beneficial effects at the organismal level. Reconciling both opposites requires reevaluating the probable evolutionary origin and role of peptidic brain hormones that direct steroid hormone synthesis. Do e.g. Luteinizing Hormone in vertebrates and Prothoracicotropic Hormone (PTTH: acting through the Torso receptor) in insects still retain an ancient role as toxins in the early immune system? Does the functional link of some neuropeptides with Ca(2+)-induced apoptosis make sense in endocrine archeology? The endocrine system as a remnant of the ancient immune system is undoubtedly counterintuitive. Yet, we will argue that such paradigm enables the logical framing of many aspects, the endocrine one inclusive of both male and female reproductive physiology.

 

[LeeLemonoil]

Nature, Calcigender, Nurture: Sex-dependent differential Ca2+ homeostasis as the undervalued third pillar. - PubMed - NCBI

All papers also open interesting perspective on the evolutionary roles of estrogens and androgens

 

[Mauritio]

I think you @haidut posted a study somewhere (androsterone thread?) about the relation of two specific hormones to each other influencing homosexuality. And I also read posts from several forum members that said their hormonal status made them more/less homosexual.
Also there was a study where high metabolic mice were bisexual , I guess just due to the sheer energy they had, they just humped everything around them
Maybe that is even natural behaviour, who knows...