Although genes could now have a very important effect on men’s sexuality, the environmental impact is still significant

In the largest study on the matter up to date, scientists from Illinois have investigated the DNA of hundreds homosexual men and have found revolutionising results that show that being gay could have a strong genetic influence.

Although the genome is a vast structure, home to thousands of genes, there were two very specific areas contained in it that were analysed in detail. Both these areas have been known by the scientific community for quite some years. For example, one of them, located in the X chromosome, and called Xq28, was first suspected to be related to homosexuality in a smaller study in 1993; whereas the other one, 8q12 in chromosome 8, was discovered in 2005. The aim of this experiment was to confirm these areas had some effect on sexuality in men and investigate how they caused this effect.

Overall, 818 men, all gay, volunteered for this project. This is almost 20 times more people than in the study in 1993. But to make it reliable as well as statistically accurate, many of the test subjects were brothers; in some cases, even non-identical twins! Having two closely related individuals with similar genetic makeup can make differences in their genome stand out and their distinct effect on the phenotype much easier to find. Using DNA collected over many years from blood samples, the scientific team looked closely at these men’s gene sequence. They were looking for small differences in the coding between brothers, specifically for single nucleotide polymorphisms, which are changes of only one base or nucleotide in a gene. After all the DNA samples were analysed, 5 single changes in the nucleotides were observed, and most occurred in these two regions of the genome.

What makes this study’s results worth considering is the fact that the only feature all these men shared was their sexuality: they were all gay. They varied in every other physical feature; so any change in those areas of their genome that was common to all men had to be related to their sexual orientation.

But both Xq28 and 8q12 are filled with genes, so although we know almost certainly that there are genes in there related to homosexuality, there is still not a distinct list of genes that could cause someone to be gay. Finding them hidden in these large areas full of coding is the team’s next task.

This discovery has, as could be expected, grave implications. It could help resolve all discrimination against gay people, and show that their sexual orientation is not a choice, but actually who they are. But unfortunately, it could lead some people to consider homosexuality as a biological mistake or a negative mutation, and even resort to genetic engineering to identify and remove ‘gay genes’ from embryos. This is wrong on many levels, but the most related to this article is that a person’s sexuality is not only defined by their genes, but is also affected by the environment they live in, so changing their genes is unnecessary and would not prevent homosexual people from being born.


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