Homosexuality Is Driven by Biological Factors, So Stop Calling It A Choice

searching for "gay genes"

The current discovery is in line with numerous twin studies conducted in the past that suggested same-sex desire is a heritable trait.

The search for "gay genes" started in 1993 when Dean Hamer connected male homosexuality to a region of the X chromosome. The most recent study was published in 2019. As genome sequencing became more accessible and less expensive, more gene candidates with potential associations to gay behavior have surfaced. A gene named SLITRK6 that is active in the diencephalon, a part of the brain that varies in size between people who are homosexual or heterosexual, was discovered by so-called genome-wide association studies.

Additional gene candidates that potentially affect sexual choice have been found through genetic research in mice. A 2010 study related the fucose mutarotase gene to sexual preference. Female mice with the gene deleted were drawn to female smells and chose to mount females over males.

Other research has demonstrated that the deletion of the TRPC2 gene can make female mice behave more like male mice. Male mice deficient in TRPC2 no longer engage in aggressive behaviors toward other males and begin sexual activities with both males and females. TRPC2 is a protein that is expressed in the brain and helps to recognize pheromones, which are chemicals emitted by one member of a species to induce a response in another.

It appeared exceedingly unlikely that a single "gay" gene exists given the number of gene candidates that have been linked to homosexuality. The recent study, which discovered five novel genetic loci (fixed locations on chromosomes) related with same-sex activity, provides additional evidence for this theory. Two of these loci were found in both men and women, two in males alone, and one in women.

How might the same-sex behavior be affected by these genes?

The fact that some of the genes from men found in Ganna's study are connected to olfactory systems, a discovery that has similarities to the research in mice, intrigues me. Other gene polymorphisms discovered by Ganna's team may be related to the regulation of sex hormones, which other researchers have argued is important in influencing how the brain develops in ways that affect sexual behavior.

Despite having an X and Y chromosome and being genetically male, males with androgen insensitivity syndrome can develop feminine genitalia and are typically raised as girls. They are also attracted to men. This implies that testosterone is necessary to "masculinize" the prenatal brain; otherwise, the infant will grow up desiring men.

Similar to this, girls with congenital adrenal hyperplasia, a genetic disorder, are exposed to exceptionally high quantities of testosterone while they are developing in the womb. This may masculinize their brains and increase the likelihood that they will become lesbians.

The hormonal changes that occur during pregnancy may also have an impact on the development of a fetus's brain. Hormone manipulation during pregnancy causes homosexual conduct in the offspring of rats.

Why is there homosexual behavior?

Many theories have been put out to explain how homosexuality can help pass down familial genes. One theory revolves around the idea of "kin selection," where individuals seek to guarantee the genetic heritage of their family is passed on to succeeding generations. Gay uncles and aunts are examples of "helpers in the nest" who support the family tree by raising the offspring of other family members.

The notion that homosexuality is a "trade-off feature" is another possibility. For instance, certain genes help women become more fertile, but if these genes are expressed in men, they can make men more likely to be homosexual.

In the animal kingdom, sexual behavior is very varied and controlled by complex systems. It is not possible to forecast sexuality by looking into a DNA sequence as if it were a crystal ball, as it is with other complicated behaviors. Such actions result from combinations of hundreds, possibly thousands, of genes and how the environment controls them.

There is a strong biological basis for sexual orientation that is programmed into the brain prior to birth based on a combination of genetics and prenatal environment, none of which the fetus chooses, despite the fact that there is no single "gay gene."