Two to six percent of people self-identify as having predominantly homosexual attractions and, while there are many social and political theories on why, what does science say?
Is being gay genetic and, if so, do we all have a gay gene?
- In the nineties, two studies using the human genome project found that gay men have a higher number of homosexual relatives compared to heterosexual men and that gay siblings have similar linkages on their X chromosome, showing a high level of genetic heritability.
- A more recent study of four hundred and nine gay siblings also found linkages in a specific region of the X chromosome labelled Xq28 and in another region of chromosome 8.
- Furthermore a 2014 analysis of fifty years of research found gay men are more likely to have gay brothers compared to straight men and lesbian women are more likely to have lesbian sisters, further suggesting the traits are genetically linked and passed on.
- But, if homosexuality is, in fact, genetic, doesn’t this create a paradox? While some gay people, still have children, overall they have 80% less children than heterosexuals, so wouldn’t the genes not be passed down and eventually die out?
- Well, a recent UCLA study used epigenetics to propose that everyone has a gay gene, but it’s whether or not the attachment of a methyl group to specific regions of DNA is triggered and turns it on.
- Epigenetics is the study of how your environment can chemically modify your genes. Like, how a queen ant’s nutrition and pheromones can chemically alter an ant embryo to either produce a soldier or worker ant based on what’s needed for the colony.
- The UCLA study used gay and straight male twins and found that a specific methylation pattern was closely linked to sexual orientation.
- The model was able to predict the sexuality of men with 70% accuracy, but this data used a small subset of people, and there is some controversy around the research.
- Ultimately, a specific gay gene has not been found, but scientific evidence does suggest that human sexual orientation is strongly linked to genetics and tightly regulated at the molecular level.
Increases in Homosexuality
- It’s even been found that giving birth to a son increases the odds of homosexuality in the next son by 33% relative to the baseline population. If an older brother is from a different mother, there is no effect seen.
- This has led some researchers to believe that male pregnancy triggers a biological mechanism that affects the mother’s successive births. A meta-analysis also found that statistically, homosexual men have more older brothers than heterosexual men.
- Another study found that women exposed to high levels of testosterone in utero have higher rates of being not straight.
- So, why does this happen? The gay uncle hypothesis suggests that gay members of a family that don’t reproduce still increase the prevalence of their family’s genes in future generations by helping to provide resources for offspring that they’re related to. After all, it’s not just survival of the fittest individual, but the fittest family.
- Studies also show that there are lower levels of hostility and higher levels of emotional intelligence, compassion and cooperation in gay men, which may also increase altruism and survival in human groups.
- Another hypothesis suggests that genes from homosexuality are ultimately coding for attraction meaning female relatives of gay men who share the same gene will also have stronger attractions to men, providing an evolutionary advantage. And, studies have shown that these females have more babies on average. The same would be true of lesbians and their straight male relatives.
The famous scientist E.O. Wilson once said “Homosexuality gives advantages to the group. A society that condemns homosexuality condemns itself.”
- Historically, science has not been kind to the queer community. In the past, it was generally accepted that the brains and bodies of homosexuals were presumed to be of lower status, with a popular belief that homosexual behaviour was a result of defective development.
- Even some LGBTQ2S people fear that scientific research could “other” the community and be used to exploit or hurt people. Even from the available research, it’s clear that most studies only focus on gay men and neglect other groups. But more research on the genetic and epigenetic factors of homosexuality will decrease homophobic laws around the world by further proving that being gay is not a choice.
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