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Discuss biological influences in gender
One biological influence on gender is the role of genes in gender development. Everybody has 23
pairs of chromosomes in their body which contain genes. These instruct a person's physical and
behavioural characteristics such as eye colour and predisposition to certain mental illnesses. One pair
of these chromosomes is called the sex chromosomes as they code for which sex you are. Males are
XY and females are XX. It is the XY in a male that distinguishes between the two sexes. Chromosomes
are found to have an impact on a person's external and internal genitalia.
At the start of prenatal development all individuals start out the same so are both sex neutral but if
anything appear physically more female. A few weeks after conception both male and female
embryos have external genitalia that look essentially feminine. Then, around 3 months into the
pregnancy if the baby is meant to be male, the testes will begin to produce testosterone which
causes the external male genitalia to develop. Genetic transmission explains how individuals acquire
their sex and it may also explain some aspects of gender (whether a person feels male or female)
because of the link between genes and genitalia and hormones. Genetic transmission also explains
certain aspects of gender roles and sex typed behaviour. For example, women are often the child
carer therefore nurturing has been passed on through natural selection. This ensures that future
generations also behave in this way and so survive.
Androgen insensitivity syndrome demonstrates the interaction between nature and nurture in
gender development. Androgens are male hormones so for example testosterone. Some XY
individuals have insensitivity to this hormone, so their bodies' tissues do not respond to the effects
of the hormone. In extreme cases this can lead to no external male genitalia developing. Such
individuals are usually identified as female at birth and so raised as boys; however some are correctly
identified and raised as boys. A case study of androgen insensitivity was reported in one family from
the Dominican Republic and investigated by Imperato-McGinley et al (1979). Four children in the
Batista family were born with external female genitalia and raised as girls. The large amounts of
testosterone produced during puberty caused their male genitalia to appear. These children were
genetically XY but had not developed male genitalia because of an inherited gene that caused
androgen insensitivity. Often the girls will accept their change of sex without difficulty. One
explanation offered is that they had never really taken on their feminine role because a number of
relatives had had similar experiences and therefore they expected to eventually become boys.
The role of hormones can be seen by studying individuals who have been exposed prenatally to
abnormal levels of hormones (intersex people). Normally external genitalia correspond to sex but
this is not always the case as shown in those who suffer androgen insensitivity syndrome. Female
embryos exposed to male hormones, for example, those whose mothers were given drugs during
pregnancy, can be born with enlarged labia resembling a penis. This clearly demonstrated the role
that hormones play in determining the physical aspects of gender.
Hormones can also be used to explain the differences between sexes with brain development.
Geshwind et al (1987) found that sex differences may be caused by the effects of testosterone
levels on the developing brain. Male brains are normally exposed prenatally to more testosterone
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When this is not the case and girls are exposed to high levels of testosterone then they
will often develop a "masculine" brain. This may be why David Reimer felt like a boy even though he
was raised as a girl; because he had a masculinised brain.
The effects of testosterone on the brain have been confirmed by animal studies.…read more