The Role Of Genes And Hormones

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The role of genes in gender development - A01

Sex - is a biological factor, whether a person is genetic male or female...Gender - refers to a person's sense of who they are - this sense of maleness and femaleness

  • Each person has 23 pairs of chormosomes ( in each cell of the body) Each of these carry hundreds of GENES containing instructions about physical and behavioural characteristics. One pair are called 'Sex chormonsomes' - determine a persons sex - XX is female and XY is male.
  • There is usually a direct link between an individual's chromosome sex and their external genitalia (****** or penis) and internal genitalia ( ovaries or testes)
  • During prenatal development all individuals start out the SAME - a few weeks after conception both male and female embryos have external genitalia that look essentially feminine. When about 3 months old, if its to develop as MALE, the testes normally produce the male hormone TESTOSERONE which causes male external genitalia to develop.
  • Genetic transmission explains how individuals acquire their sex. It may also explain some aspects of gender because of the link between genes and genitalia and hormones
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The role of genes in gender development - A02


Claimed that biological sex was not the main factor in gender development. He argued that sex of rearing was much more important and recommended that INTERSEX individuals, such a David Reimer (explained below) could be successfully as being raised as either boy or girl. However this famous case study of David did not support this. The outcome has been further supported by subsequent research, for example that of REINER AND GEARHART who studied 16 genetic males born with almost NO PENIS. TWO were raised as males and the remained MALE. The remaining 14 others raised as FEMALES, and of these, 8 RE-ASSIGNED themselves as MALES by the age of 16. Such research suggest that biological facotrs have a key role in gender development.

DAVID REIMER... Was born a boy along with his identical twin. At the age of 6 mths they were both circumsiced to cure a urination problem. Tragically the operation on David was botched and David's penis was all burnt off. So his parents made the decision with help from Dr Money to remove his penis and testes and raise him as a girl (As Money claimed that gender is learnt) He recieved hormones and so develop as a girl through puberty, but inwardly he felt like a boy and so reverted back to a BOY. This shows how biological sex is the primary factor of gender.

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The role of hormones in gender development- A01

Chromsomes intiate a person's sex but most gender development is acutally governed by HORMONES. These are both produced prenatally and then at puberty. Hormones influence the development of genitalia and/or affect the development of the brain, both of which influence gender behaviour.

DEVELOPMENT OF GENITATLIA - The hormones in gender development can be seen by studing individuals who have been exposed to abnormal hormone levels. Normally external genitalia are in accord with genetic sex. However in some cases a genetic male embryo may be exposed to too little testosterone and the result is the male when born looks like a female. This is due to AIS - Androgen Insensitivity Syndrome. Testosterone is a androgen (male hormone) and some XY have an insensitvity towards it (don't accept it). There body tissues do no respond. And so in extreme cases some males have no external genitalia and are identified as FEMALE at birth and raised as girls. A study of a Dominican Republic family with AIS, found that the 4 child born with XY but had no external male genitalia's were raised as girls, until puberty when they strated producing testosterone and started their genitalias to appear. The girls accpected their change without much difficulty, prehaps because this had happened to other family members and there expected to really become boys.

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The role of hormones in gender development- A01

Development of genitalia : Conversly females exposed prenatally to relatively large doses of male hormones, can be born with AMBIGOUS GENITALIA (swollen labia resembling a penis called CAH). These individuals are usually content with this gender assignation. However research from BERENBAUM and BAILEY has indicted that they are often interested in male type activities, proberly becasue of the exposure to testosterone. 

BRAIN DEVELOPMENT - Sex differences explained... Males brains are different from female brains such as males have systemisig brains and females empathising brains. Girls are better with social skills, but less good a spatial navigation etc.

Greschwind and Galaburda were the first to suggest such sex difference may be caused by the effects of testosterone levels on the developing brain. So if males are prenatally exposed to testosterone it will lead to a masclinised brain, and with a female it would lead to masclinised brain as well. This may explain why DAVID felt like a boy in a girls body, and why some girls grow acting like a 'tomboy' 

supported by QUADAGNO et at, who found female monkeys exposed to testosterone prenatally were more rough and tumble and aggressive compared to other females

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The role of hormones in gender development- A02

However genes and hormones are not the whole story either. Genetic sex does not match external genitalia in cases of abnormal hormone exposure, as we have seen, and even hormones do not produce a simple formula for establishing gender. The eventual outcome for each individual is what appears to be a complex and unpredictable combination of genes, hormones, sex and rearing.

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A03 - Nature - Nurture Debate

S: When considering the role of genes and hormones play on gender development the nature-nurture debate should be considered. The nature side of the debate is supported by David Reimer as despite being raised as a girl from 6 months old he still felt like a boy inside. This implies that or nature/biology is more significant in gender development than social factors and the way you are nurtured.

E: It would suggest that gender cannot be learned and that it has a purely biological basis, however the nurture side of the debate should also be considered. As the Batista family suffered from AIS they would have been prepared from a young age for the gender change so social factors could have also contributed to how easy the sex change was. 

E: This casts doubt upon whether gender development is solely a result of our biology and implies the way you are nurtured may also influence your gender. Therefore an interactionistapproach would be most appropriate when explaining the relationship between genes and hormones and our gender development.

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A03 - Real world application

S: An interesting slant on the issue of biological determinism is showin in a dilemma faced by the International Olympics Committee. 

E: Since 1968  it has tested the genetic sex of all athletes and excluded all but XX females and XY males, which meant that AIS individuals would no longer compete. In 1991 there was a ruling that genetic sex would no longer determine entry to the games. Individuals are now exculded from women's events only if they are obviously physically male (BOWN)

E: In other words genetic sex no longer determines gender. Therefore research into the roles of hormones on gender has had implications on society and now people with AIS are no put at a disadvantage. 

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