The physiological mechanism of gay generation

Everyone has the right to love and be loved. Love cannot be defined. The love of the gay community may not conform to so-called “tradition,” but it is only one type of love diversity, and it should never be rashly concluded as a mental illness.

In fact, the generation of gay is not simple. Many studies have explored the “differences” in gay bodies. Today, let us explore the mystery of its occurrence together.

What is gay?

Definition of gay

As a sexual orientation, gay refers to an individual’s emotional, sexual attraction to, and sexual behavior with, members of the same sex. This preference is part of an individual’s identity and is one of the natural and normal diversity of human behavior.

Manifestations of gay

There are diverse manifestations of gay behavior, including but not limited to emotional attachment, sexual attraction, and sexual behavior.

However, not all same-sex sexual behavior means that an individual is gay. Some non-gays may also engage in same-sex sexual behavior in specific situations, a phenomenon known as “situational gay”. The identity of gay people is usually based on psychosexual orientation to the same sex, not just sexual behavior.

Sexual orientation is a complex human characteristic that involves multiple dimensions of emotion, behavior, and social interaction. Diversity in sexual orientation has existed throughout the long history of human society, but scientific understanding of it has come relatively late. With the progress of science, humans have begun to explore the biological basis behind sexual orientation, especially the physiological mechanisms of gay.

Although gay has a different history and manifestation in different cultures and societies, its prevalence among different races and cultures around the world suggests that it may be a natural variation rooted in human biology. Next, let’s explore its genetic and physiological mechanisms.

Genetic factors of gay

Some studies have shown that the occurrence of gay is determined by genetic factors, and the incidence is higher among individuals with closer family relationships. There are two classic pieces of evidence for this conclusion:

① Bailey and Pilleast’s experiment:

Known: identical twins have the same genes, while fraternal twins have 50% of the same genes.

Hypothesis: both twins are gay → consistent; only one is gay → inconsistent.

Results: concordance rate of identical twins: 52%; concordance rate of fraternal twins: 22%.

② A survey of specific families found that the offspring with a family history of gay have a higher chance of being gay.

It can be seen that gay is hereditary!

However, the genetic factors of gay are very complex, involving numerous genetic loci, and each locus has a relatively small effect.

The relationship between gay and genes

Recent genome-wide association studies (GWAS) have shown that gay is not determined by a single gene, but by the combined influence of multiple genes. These genes are located throughout the genome, and the influence of a single gene is minimal, but together they can explain 8-25% of same-sex sexual behavior.

This complexity means that it is impossible to predict an individual’s sexual orientation through genetics, and it also shows that the genetic basis of sexual orientation is not a simple dichotomy.

Gay and epigenetics

In addition to genes, scientists have discovered the potential role of epigenetics in the formation of sexual orientation. Epigenetics refers to the chemical modifications of the human genome that change gene activity without altering the DNA sequence, and can be influenced by environmental factors.

Scientists have proposed a new model, suggesting that gay may be due to the failure of maternal sex-specific epigenetic marks (“epimarks”) produced during embryonic development to be erased, thereby affecting the direction of development of the sex characteristics of the offspring. These epigenetic marks are produced in the parents, but may lead to inconsistencies in the sex characteristics of the offspring, thereby affecting sexual orientation.

Gay and maternal immune hypothesis

Studies have found that for every older brother a mother has, the probability of her younger brother being gay increases by about 33%. This phenomenon is also known as the older brother effect.

According to the maternal immune hypothesis, every time a male fetus is born, the mother’s immune system gradually produces male-specific antigens associated with the Y chromosome. This immune response becomes increasingly stronger, affecting the sex differentiation of the brain and thus the sexual orientation of the son. Subsequent studies have also found that the mothers of gay sons, especially those with older brothers, have significantly higher levels of neuroligin 4 Y-linked (NLGN4Y) than the mothers of heterosexual sons.

Sex hormones

The classic view is that during embryonic development, exposure to high concentrations of androgens promotes male behavior and a preference for women, while exposure to low levels of androgens promotes female behavior and a preference for men.

Estrogen has a similar effect in some respects, and research on it has also shown that the effects of sex hormones during embryonic development have a significant irreversible impact on adult sexual orientation, which cannot be offset by subsequent remedial actions.

It can be seen that early exposure to sex hormones plays a key role in the formation of male and female sexual orientation. Animal models and human studies have shown that sex hormones have an important influence on brain development and the sexual differentiation of sexual behavior.

So how does this influence occur?

Most people believe that the possible mechanisms by which sex hormones affect brain differentiation and individual sexual orientation are related to the effects of sex hormones on brain neurons, and there are two main types.

Indirect effects of sex hormones on brain neurons: They form complexes by binding to intracellular receptors in specific parts of the brain, and then undergo nuclear translocation to bind to specific hormone response elements on genes, affecting the expression of specific genes and protein synthesis.

The direct effect of sex hormones: By changing the membrane permeability of neurons in certain brain regions, it can affect the release, uptake, inactivation, and synthesis of neurotransmitters, as well as the sensitivity of postsynaptic membrane receptors. This can affect the sexual differentiation of the brain and the sexual orientation of the individual, thereby producing specific neuroendocrine effects.

Sex hormones have a significant effect on brain development and the gender differentiation of sexual behavior. Changes in hormone levels during the fetal period may lead to abnormal gender differentiation of the brain, which can affect an individual’s sexual orientation. Are there any differences in the brain between gay and heterosexual people?

Brain differences

The relationship between gay and neurobiology is a complex and multifaceted field of research. In recent years, scientists have explored this topic using a variety of neuroimaging and anatomical methods. Some studies have shown that there are differences between the brains of gay people and non-gay people. Among gay people, the distinction between the brains of gay men and gay women becomes blurred, and they are both transitioning to the opposite sex.

Hypothalamic structure

Studies have shown that the volume of the INAH 3 (one of the four anterior nuclei of the hypothalamus) is much larger in heterosexual men than in gay men. In addition, studies have shown that there are more cells in the anterior hypothalamus of gay men.

Size of the anterior commissure

Studies have found that the anterior commissure (bundle of fibres in the forebrain) is larger in gay men than in heterosexual men and women. This structural difference may be related to cognitive functions and cerebral hemispherisation.

Brain response and smell

In terms of olfactory stimuli, gay men respond to androgen derivatives (such as AND) in a similar way to heterosexual women, but not to heterosexual men. This suggests that olfactory processing may be related to sexual orientation.

Differences in grey matter volume

Some studies have shown that the gray matter volume of certain brain regions in gay men differs from that of heterosexual men. For example, the gray matter volume of the right posterior central gyrus is negatively correlated with the degree of gay sexual orientation, while the gray matter volume of the left amygdala is positively correlated with the degree of gay sexual orientation.

Resting-state functional connectivity

At rest, the local coherence and functional connectivity of gay men also show different characteristics from those of heterosexual men.

They have lower local coherence in some brain regions and weaker functional connectivity with other brain regions (reHo reflects the synchronization or coherence of neural activity in adjacent brain regions).

The physiological mechanism of gay is not yet very clear, and scientists are still decrypting it. This exploration is not only a respect for human diversity, but also an in-depth understanding of biological complexity.

In addition to the physiological mechanism, we may be more familiar with the psychosocial causes that lead to it.

Psychosocial causes

overview

Family environment factors

①The parents of gay people may not be able to provide appropriate role models for their children’s gender roles, resulting in an incomplete gender self-identification in their children.

②The misfortune of the parents’ marriage, such as constant family quarrels or the parents’ divorce, may affect the development of the child’s sexual orientation.

③The lack of sex education may lead to problems in the development of an individual’s sexual orientation.

Personal experience

①The importance of first sexual experience is emphasized by the “gap-filling” theory, which holds that once a certain sexual behavior first fills the gap in an individual’s sexual behavior, it may become fixed and form a lifelong sexual orientation.

②Serious setbacks in heterosexuality: If a person is frustrated in their interactions with the opposite sex, has had unpleasant experiences, and heterosexual feelings cannot develop normally, and at the same time is tempted by the same sex, they may develop a gay orientation.

Social environmental factors

①A specific single-sex environment, such as the military or prison, may affect an individual’s sexual orientation, and heterosexuality may become gay.

②If an individual lives in an environment with gay people, they may become gay through learning and imitation.

In general, the emergence of gay is a multi-factor, multi-level phenomenon involving multiple fields such as biology, psychology, and sociology. It is currently impossible to give a decisive cause.

However, there is no doubt that research into the causes of gay can help us to improve scientific understanding, eliminate prejudice and discrimination; promote health and well-being, enhance identity and social support; and promote the formulation of social policies and laws.

Let’s have more understanding and less misunderstanding!

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