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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.
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.
But, could we ever genetically get rid of homosexuality?
Watch our second video where we discuss if it's possible and the implications
of continued study into this field.
And subscribe for more weekly science videos every Thursday.


大家都有同性戀基因嗎? (Does Everybody Have A Gay Gene?)

1062 分類 收藏
韓澐 發佈於 2017 年 7 月 28 日    bamboowater 翻譯    黃艾瑄 審核
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