Section:GDN 1N PaGe:3 Edition Date:190830 Edition:01 Zone: Sent at 29/8/2019 21:02 cYanmaGentaYellowbl
Friday 30 Aug ust 2019 The Guardian •
News^3
Scientists bust myth of single ‘gay
gene’ that causes homosexuality
Nicola Davis
Scientists have quashed the idea that
a single “gay gene” exists, instead
fi nding that homosexual behaviour
is infl uenced by a multitude of genetic
variants which each have a tiny eff ect.
The researchers compare the situa-
tion to factors determining a person’s
height, in which multiple genetic and
environmental factors play roles.
“ [This study] highlights both the
importance of the genetics as well as
the complexity of the genetics, but
genetics is not [the] whole story,” said
Dr Benjamin Neale, co-author , from
the Broad Institute in the US. Writing
in the journal Science , an interna-
tional team of researchers report how
it is thought non-genetic factors before
birth, such as the hormonal envi-
ronment in the womb, also play an
important role.”
The team then looked at which
genetic variants might be behind
the link, using data from more than
400,000 participants in the UK
Biobank project and more than 68,
individuals whose data was collected
by the company 23andMe.
Researchers found fi ve genetic var-
iants – tiny diff erences in DNA – that
showed a clear link to same-sex sex-
ual behaviour, two in both men and
women, two found only in men and
one found only in women. The team
believe one, found only in men, might
be involved in sex hormone regu-
lation, not least because it is linked
to male-pattern balding. Even takenThieving bears prefer premium
honey, Turkish beekeeper fi nds
Alison Rourke
A beekeeper in Turkey who was har-
assed by a particularly persistent group
of bears has discovered a profound
truth: the animals have expensive
tastes when it comes to honey.
Ibrahim Sedef, an engineer from
Trabzon, north-east of Ankara on the
Turkey’s Black Sea coast, struggled to
keep his bee hives out of the paws of
local bears, despite building storage
houses and metal cages.
Over three years, he estimates he
may have lost more than $10,
(£8,000) worth of honey.
Food decoys, including apples,
failed to divert the intruders. So hedecided to set up recording equipment
to track the bears and, inadvertently,
embarked on animal testing of a dif-
ferent kind.
Sedef set up four bowls; three
contained diff erent types of honey- fl ower, chestnut and Anzer – and
one had cherry jam. He wanted to see
which one the bears preferred.
The footage revealed they had
very expensive taste. Their favour-
ite, Anzer honey , is believed to be the
most expensive honey in the world.
It is produced from the nectar of 90
fl owers that grow only in the moun-
tains of the Anzer plateau.
In addition to being delicious to
bears, some believe Anzer honey has
healing qualities for a long list of ail-
ments, including stomach pains, hair
loss and wound treatment.
It can sell for as much as $300 a
kilogram.
Despite his losses, Sedef is philo-
sophical about his hungry visitors.
“Despite all this, when I see the foot-
age, I forget all the harm they have
done to me, and love them,” he said.
Brown bears are the largest carni-
vores in Turkey and mainly live near
the Black Sea and Eastern Anatolia
regions.they drew on existing genetic data-
bases to conduct the largest study yet
into genetics and same-sex sexual
behaviour.
In the fi rst part of the study, they
looked at data from about 500,
individuals collected as part of the UK
Biobank project: about 4% of men and
nearly 3% of women said they had ever
had a same-sex sexual experience.
By looking at sexual behaviour ,
they estimated that about a third of
the variation in same-sex behaviour is
explained by genetics. That, they say,
chimes with previous twin studies that
put the fi gure at about 30% to 50%.
Dr Brendan Zietsch , co-author of
the research from the University of
Queensland in Australia, said that
did not mean the rest was due to
upbringing or culture. “For example,together, though, these fi ve genetic
variants explain less than 1% of the var-
iation in same-sex behaviour among
participants – suggesting many other
variants are involved, each playing a
very small role.
Neale stressed that the scale of
the infl uence of non-genetic factors,
complexities of sexual behaviour,
and diffi culties in precisely measur-
ing the size of any eff ects means it is
not possible to use genetic informa-
tion to predict whether an individual
will have same-sex partners.
The study provides a number of
insights, including that there is over-
lap between genetic predisposition to
same-sex sexual behaviour and traits
such as openness to experience , as
well as predisposition to mental health
problems. “One possibility is that
stigma associated with same-sex sex-
ual behaviour causes or exacerbates
mental health issues. This could cre-
ate a genetic correlation ,” said Zeitsch.
The authors also say their fi ndings
call into question the idea that sexu-
ality exists on a single scale.
“[There] seem to be genes associ-
ated with opposite-sex attraction and
other genes associated with same-sex
attraction, and these are not related,”
added Zeitsch. “These results sug-
gest we shouldn’t be measuring sexual
preference on a single continuum from
straight to gay, but rather two separate
dimensions : attraction to the same sex
and attraction to the opposite sex.”
The idea that genetics might play
a role in same-sex attraction was pro-
pelled into the spotlight in 1993 when
Dean Hamer, a scientist at the US
National Cancer Institute, and his team
found links between DNA markers on
the X chromosome and male sexual
orientation. The fi ndings caused con-
siderable controversy, with the media
dubbing the fi nd the “gay gene”.
Hamer said he was delighted by
the latest research. “This provides yet
another strand of evidence, another
approach, showing there is a strong
and signifi cant genetic contribution
to people’s sexual behaviour, ” he said.
However, unlike Hamer’s work, the
latest study does not show any special
importance of the X chromosome. The
researchers say that is not surprising,
adding the previous fi ndings would
not meet today’s bar for importance,
and were based on a small sample size.
A website set up by the research-
ers gives a clear message: “This study
provides further evidence that diverse
sexual behaviour is a natural part of
overall human variation.”
The study has limitations includ-
ing that it is based mainly on people
of European ancestry, while the age
range of participants does not fully
refl ect that of the wider population. It
also relied on self-reported behaviour.▲ The bears’ favourite was Anzer
honey, the four-bowl test revealed4%
Proportion of men who said they
had had a same-sex experience33%
Rough proportion of variation in
behaviour explained by genetics5
Number of genetic variants found to
show clear link to same-sex activityIn numbers
▼ A giant rainbow fl ag is carried
along the crowded seafront during
Brighton Pride earlier this month
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