RAINBOW IN THE DNA | An artist's sketch of the DNA--the molecule which holds the secrets to the genetic basis of gender and human sexuality. Image taken from: Getty Images |
The
UPLB Genetics Society will illuminate the minds of the youth as they feature the genetic basis of gender
through a rainbow-filled exhibit and week-long activities on April 9-13, with
the theme, “Beyond Binary: Exploring the
Genetic Realm of the Gender Spectrum”.
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Gender,
defined as “the socially constructed characteristics of men and women” by the
World Health Organization, is a fundamental aspect of an individual. It affects
how a person thinks, acts, would establish relationships, would express one’s
self, and many others. As revealed by findings in genetics, gender is now
understood as something that is influenced by our genes, as well as by the
environment which could be sociological, psychological or physiological. This
understanding provides us an additional, scientific perspective in viewing
gender as an essential facet that defines us as a human. Here, we will be
exploring the genetic links to the categories associated with gender such as
biological sex, gender identity and gender expression, as well as sexual
orientation. These categories are based on “The Genderbread Person” which
provides us a clear illustration of the gender spectrum.
Biological Sex
Biological
sex is based on a person’s chromosomes, specific genes, hormones and sex
organs. Generally, in humans, females have two X chromosomes while males have
an X and a Y chromosome. The two X’s in a female are inherited both from her
parents. But in the case of the male, only the father can give the Y chromosome
while the mother gives the X. In the Y chromosome, there is a gene called SRY (referring to sex-determining region
in Y) which codes for hormones that activate the formation of male sex organs.
In contrast, females do not have a Y and therefore lacks SRY gene which leads to the formation, instead, of female sex
organs. However, there are cases when a person is considered as an intersex, wherein his/her internal and
external genitalia are inconsistent (i.e. male-internal, female-external).
Medical disorders such as congenital adrenal hyperplasia, androgen
insensitivity syndrome and 5-alpha reductase deficiency cause a person to be intersex.
Gender Identity
Gender
identity is how you view your own gender. Several researches have suggested
possible links to genetics and gender identity. In a 2003 study conducted by
researchers in the University
of California at Los Angeles involving mice embryos, it was found out that
there are a total of 54 genes which have different activity levels in the mice
brain depending on gender. In the 10-day old embryonic mice (days prior
to the emergence of sex organs), they discovered that 18 genes were more active
in the male embryonic brains while 36 genes showed higher activity in the
female embryonic brains. In another study conducted by Hare and other
researchers in 2009, it was shown that there is a considerable link between
transsexualism (having a gender identity of the opposite sex) and the AR (Androgen Receptor) allele. The
results showed that transsexual males have a longer AR repeat lengths than non-transsexual males. The researchers
explained that a longer repeat in the AR allele
lessens the binding of the AR protein to its-coactivator which reduces
testosterone signaling. This then leads to incomplete brain masculinization and
the manifestation of a female gender identity in transsexual males.
Gender Expression
Gender
expression is how you show your gender through your manners, actions, clothing
style, etc. Toy-preference tests involving children are commonly done in
genetic studies to examine gender expression. Accordingly, the toy a child
prefers would indicate his/her gender expression. Playing with a car would show
maleness and playing with a doll would exhibit femaleness. It is believed that
there are more boys than girls who prefer cars and more girls than boys who
prefer dolls because they were parentally guided to play with those toys.
However, a 2002 paper published in Evolution
and Human Behavior reveals that the same toy preference is exhibited in
monkeys – that is, without parental influence. The researchers have observed
that male monkeys tend to prefer toys that exhibit movement while females play
with toys that exhibit ‘nurturance’. They explained that toy-preference among
male and female primates may have been a consequence of evolution and is
therefore influenced by genes which were favored in different sexes. The study,
however, pointed out that gender socialization can also steer object
preference.
Sexual Orientation
Sexual
orientation is based on whom you are attracted to. It can be broken down into
two sub-categories: sexual attraction (the want for a sexual relationship) and
romantic attraction (the want for an emotional relationship). In 1993, Dean
Hamer and his colleagues pointed out that in the majority of male individuals,
a locus in the q28 region of the X chromosome could be influencing male sexual
orientation. How did they arrive at this conclusion? First, they found out in
their study that a homosexual male had more homosexual relatives in the mother
side than in the father side. This means that the locus they are looking for is
more likely in the X-chromosome. Then, they noticed that the sharing of Xq28
allele is higher homosexual male siblings. This led them to associate the Xq28
allele with male sexual orientation.
While
aspects in gender can be understood in the genetic perspective, it is important
to realize that gender is not influenced solely by genetics. There are other
environmental factors that could influence gender such as the individual’s
sociocultural atmosphere, hormones, brain wiring, and many others. Furthermore,
research findings linking genetics and gender ought not to be ascertained as
settled facts. Genetic research about gender is still in its infancy and the
knowledge about its genetic basis is still expanding. Nonetheless, these
researches are shedding new light and are widening our understanding on how our
genes influence our gender and sexuality. These emerging studies truly attest
that gender is beyond binary as revealed by the genes that we possess.
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The
BIO 30 Week will have the following activities: Exhibit Opening and GENEWS
Launching, Genetics Quiz Contest, Print-All-You-Can and 3rd BIO 30
Tutorials.
References:
Alexander, G. M., & Hines, M. (2002).
Sex differences in response to children's toys in nonhuman primates
(Cercopithecus aethiops sabaeus). Evolution
and Human Behavior, 467-479.
Hamer, D. H. (1999). Genetics and Male
Sexual Orientation. Science, 803.
Hare, L., Bernard, P., Sánchez, F. J.,
Baird, P. N., Vilain, E., Kennedy, T., & Harley, V. R. (2009). Androgen
Receptor Repeat Length Polymorphism Associated with Male-to-Female
Transsexualism. Biological Psychiatry,
93-96.
Killerman, S. (2017). A Guide to Gender: The Social Justice Advocate's Handbook (2nd ed.).
Austin, TX: Impetus Books.
Lewis, R. (2010). Human Genetics (9th ed.). New York, NY: McGraw-HIll.
University Of California Los Angeles.
(2003, October 22). Brain May 'Hard-Wire'
Sexuality Before Birth. Retrieved from ScienceDaily:
https://www.sciencedaily.com/releases/2003/10/031022062408.htm
World Health Organization. (2018). Gender, equity and human rights.
Retrieved from World Health Organization:
http://www.who.int/gender-equity-rights/understanding/gender-definition/en/
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