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The Role of Chromosomes And Hormones In Gender

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The Role of Chromosomes And Hormones In Gender

Man up! Be more ladylike! You've probably heard these phrases a million times telling us how to be more masculine or feminine, but have you ever considered that sex and gender is largely influenced by biological factors such as chromosomes and hormones? In this article, we will explore how these factors influence sex and gender.

As you probably already know, sex is a biological, innate characteristic whereas gender is how society thinks we should express this biological feature. Therefore, although sex is directly influenced by hormones and chromosomes, gender is indirectly influenced by these as people often link biological sex and the expression of gender.

The role of chromosomes in sex and gender

Let's begin with a quick recap on chromosomes and genetics. Chromosomes are made of DNA, whilst genes are short sections of DNA that determine the characteristics of living things. Chromosomes come in pairs. There are 23 pairs in the human body (so 46 chromosomes overall). The last pair of chromosomes is what influences our biological sex. In females the pair is XX, and for males it is XY.

All normal eggs produced in the ovaries have an X chromosome. Half of the sperm have an X chromosome and the other half have a Y chromosome. The sex of a baby is thus determined by the sperm that fertilises the egg cell.

The Role of Chromosomes And Hormones In Gender XY and XX chromosomes StudySmarterXX and XY chromosome, Yzabelle Bostyn - StudySmarter Originals

If the sperm carries X chromosomes, the baby will be a girl. If it carries Y chromosomes, it will be a boy. This is because the Y chromosome carries a gene called the 'sex-determining region Y' or SRY. The SRY gene causes tests to develop in an XY embryo. These then produce androgens: male sex hormones. Androgens cause the embryo to become a male, so without them, the baby develops as a female.

The role of hormones in sex and gender

Chromosomes initially determine a person's sex, but most biological sex development comes about as a result of hormones. In the womb, hormones encourage the development of the brain and reproductive organs. Then, during adolescence, a burst of hormones induces the development of secondary sexual characteristics such as pubic hair and breast development. Males and females have the same types of hormones but in different concentrations.

Testosterone

Male developmental hormones are known as androgens, the most prominent of which is testosterone. Testosterone controls the development of male sex organs and begins to be produced at around eight weeks of fetal development.

Many psychological studies have researched the behavioral effects of testosterone, the most notable of which is aggression. For example, Van de Poll et al. (1988) demonstrated that female rats became more aggressive when injected with testosterone.

Estrogen

Estrogen is the hormone that influences the development of female sex organs and menstruation.

Besides physical changes, the hormone can cause mood changes in women during menstruation, including increased irritability and emotionality. If these effects become severe enough to be considered a diagnosable disorder, they can be referred to as pre-menstrual tension (PMT) or pre-menstrual syndrome (PMS).

Oxytocin

Although both men and women produce oxytocin, women produce it in much larger quantities than men. It plays a crucial role in female reproductive function, including childbirth. Oxytocin stimulates lactation for breastfeeding. It also reduces the stress hormone, cortisol, and facilitates bonding, especially during labour and after childbirth. That is why this hormone is often referred to as the 'love hormone.'

Some have used the fact that men produce less oxytocin to support stereotypes that men are less romantic and interested in love. However, research has shown that men and women produce the hormone in equal amounts during activities such as kissing and sex.

The Role of Chromosomes And Hormones In Sex and Gender Oxytocin stimulates lactation for breastfeeding StudySmarterOxytocin stimulates lactation for breastfeeding

How can we evaluate the role of hormones and chromosomes in sex and gender?

Many psychologists have conducted research into the role of hormones and chromosomes in sex and gender. Many have also evaluated and criticized this approach to explaining sex and gender. Below w will outline the role of chromosomes and hormones in sex and gender.

Pre-menstrual syndrome supports stereotypical views of women

The suggestion that women become emotional and irritable during their menstrual cycle due to hormones gives a biological explanation to women's feelings and moods. This could allow people to dismiss women's emotions as merely the result of biology. Therefore, many authors such as Rodin (1992) have argued that the medicalization of PMS supports patriarchal views.

Contradictory evidence

In a double-blind study, Tricker et al. (1996) gave 43 times an injection of testosterone or a placebo. Over a ten-week period, no significant differences were observed between the experimental condition (testosterone) and the control group (placebo). This suggests that hormones do not significantly influence behavior.

Keep in mind that studies of hormonal influence on gender often use small and unique samples (such as transgender individuals). This means that the generalisability of such studies can be questionable.

Oversimplified and reductionist

If biology was the only influence on behavior, we would expect a lot more differences between male and female behavior. For example, Maccoby and Jacklin (1974) found that there were significantly more differences within genders than between them.

Learning theory

Approaches such as behaviorism and social learning cite environmental factors as the driving force of gender-related behavior. This could explain cross-cultural differences in cultural behavior and transgender individuals.

The psychodynamic approach

This approach suggests that gender is a result of early childhood experiences. For example, Ovesey and Person (1973) suggested that males who exhibit female characteristics do so because of separation anxiety in early childhood. This anxiety they experienced makes them want to identify with their mother.

Cognitive explanations

The cognitive approach suggests that biological explanations of sex and gender oversimplify a complex concept. It suggests that thought processes influence gender development. But although these could be linked to the changing state of the developing brain, it remains clear that gender is not sufficiently explained through biology.

The failure to consider these alternative influences on gender and sex makes the biological approach reductionist, as it reduces gender and sex down to one factor: biology.

Research evidence

Below are a few studies which explore the role of chromosomes and hormones in gender.

Dabbs et al (1995)

Dabbs and his colleagues studied the levels of testosterone in the prison population and found that offenders with high levels of testosterone were more likely to have committed violent or sexually motivated crimes. These suggests that hormones are linked to behavior.

The Bruce Reimer case study

Brian and Bruce Reimer were twin boys born in Canada in 1965. Following a botched circumcision, Bruce was left without a penis.

Bruce's parents were directed to John Money, a psychologist pioneering his 'gender neutrality' theory, which suggests that gender is determined more by the environment rather than biological factors.

As a result, Money encouraged the Reimers to raise their son as a girl. 'Bruce', known as Brenda, played with dolls and wore girls' clothes. Although Money wrote extensively of the 'success' of this case, Bruce suffered from psychological problems, leading their parents to disclose the truth of their identity. Following this, Bruce returned to life as a male, 'David'. Unfortunately, David suffered deeply as a result of their hidden identity and committed suicide in 2004.

This case study suggests that there is some biological basis to sex and gender because despite being raised socially as a girl, David still felt uncomfortable in this gender, probably as a result of the truth of his biological sex.

The Role of Chromosomes In Sex And Gender What determines gender StudySmarterWhat determines gender?, Yzabelle Bostyn - StudySmarter Originals (Made in Canva)

Van Goozen et al. (1995)

Van Goozen studied transgender individuals who were undergoing hormone therapy as part of their transition. This means they were injected with hormones of the opposite sex. Transgender women (men transitioning to women) showed a decrease in aggression and visuo-spatial skills, whilst the opposite was true for transgender men (women transitioning to men). This suggests that hormones influence the behavior of men and women differently.

The Role of Chromosomes And Hormones In Gender - Key takeaways

  • Chromosomes and hormones influence the development of sex characteristics in males and females.
  • Males have XY chromosomes.
  • Females have XX chromosomes.
  • Testosterone influences the development of male sex organs and levels of aggression.
  • Estrogen influences the development of female sex organs and the menstrual cycle.
  • Females produce much more oxytocin than males.
  • Oxytocin stimulates lactation and the release of cortisol (a stress hormone), encouraging bonding and affection.

Frequently Asked Questions about The Role of Chromosomes And Hormones In Gender

Chromosomes do not determine gender as this is socially determined. However, chromosomes do determine biological sex. 

Many hormones affect sex and gender identity, such as testosterone, estrogen and oxytocin. 

XX for females and XY for males. 

Male

Genetically, only males have XY chromosomes. 

Final The Role of Chromosomes And Hormones In Gender Quiz

Question

What are chromosomes?

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Answer

Chromosomes are made of DNA which is made of genes that determine the characteristics of living things. Therefore, chromosomes determine the characteristics of living things.

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Question

How many chromosomes do humans have?

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Answer

23 pairs or 46 overall.

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Which chromosome influences sex?


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Answer

The last

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Question

Give the chromosome structure for males.


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Answer

XY

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What is the chromosome structure for females?


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Answer

XX

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Question

Most gender development comes about as a result of what?


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Answer

Hormones

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Question

In the womb, hormones encourage the development of ____________.


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Answer

The brain and reproductive organs.

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Question

At what stage of life do secondary sexual characteristics begin to develop? 


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Answer

Adolescence

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Question

Give an example of a secondary sexual characteristic. 


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Answer

Pubic hair, breasts

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Question

Which hormone influences male sexual development? 


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Answer

Testosterone 

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Question

What does estrogen influence?


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Answer

The development of female sexual characteristics and menstruation.

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Question

Why do women produce much larger amounts of oxytocin? 


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Answer

Because it is produced during labor and after birth to encourage lactation.

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What hormone does oxytocin reduce the production of?


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Answer

Cortisol (a stress hormone).

Show question

Question

Why have some women criticised the idea of PMS? 


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Answer

The suggestion that women become emotional and irritable during their menstrual cycle due to hormones gives a biological explanation to women's feelings and moods. This could allow people to dismiss women's emotions as merely the result of biology.

Show question

Question

Describe the Bruce Reimer case study. 


Show answer

Answer

Bruce was born a boy but due to a botched circumcision lost his penis. A psychologist called John Money advised his parents to raise him as a girl called Brenda. Despite this, Bruce suffered from confusion and depression, leading his parents to reveal his true sex. As a result he returned to life as a male called David. Unfortunately, he died in 2004 from suicide. 


This case suggests that there must be some biological basis to sex as despite being raised as a woman, Bruce never felt comfortable as a woman. 

Show question

Question

What did Dabbs et al. (1995) find? 


Show answer

Answer

Dabbs and his colleagues studied the levels of testosterone in the prison population and found that offenders with high levels of testosterone were more likely to have committed violent or sexually motivated crimes. These suggests that hormones are linked to behaviour.

Show question

Question

Describe the Van Goozen et al. (1995) study. 


Show answer

Answer

Van Goozen studied transgender individuals who were undergoing hormone therapy as part of their transition. This means they were injected with hormones of the opposite sex. Transgender women (men transitioning to women) showed a decrease in aggression and visuo-spatial skills, whilst the opposite was true for transgender men (women transitioning to men). This suggests that hormones influence the behavior of men and women differently.

Show question

Question

Give an alternative explanation of sex and gender


Show answer

Answer

Learning theories such as behaviourism and social learning theory cite environmental factors as the driving force of gender-related behaviour. This could explain cross-cultural differences in cultural behavior, transgender individuals and the fact that society is gradually becoming more androgynous.

Show question

Question

How is the biological approach to explaining sex and gender reductionist?


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Answer

It reduces sex and gender down to biological factors.

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Question

What is an atypical sex chromosome pattern?

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Answer

Sex chromosome patterns are atypical when they deviate from the typical XX/XY formations, which give us male or female characteristics. 

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Question

What is Klinefelter’s syndrome?

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Answer

Males with Klinefelter’s syndrome have an extra X chromosome (XXY), i.e., they develop small infertile testes, a slim frame, and enlarged breasts.

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What is the chromosome pattern for people with Klinefelter’s syndrome? 


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Answer

XXY

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What is Turner’s syndrome?

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Answer

Turner’s syndrome is when females lack an X chromosome, leading to a lack of breast development and infertility.

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What is the chromosome pattern for people with Turner’s syndrome? 

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Answer

X

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Question

How many chromosomes does a person with Turner’s syndrome have?


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Answer

45.

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Question

What is a physical characteristic of Klinefelter’s syndrome? 


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Answer

Overdeveloped breasts.

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What is a psychological characteristic of Klinefelter’s syndrome?


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Answer

Passivity.

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Question

 What is a physical characteristic of Turner’s syndrome?

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Answer

Under-developed breasts.

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 What is a psychological characteristic of Turner’s syndrome?

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Answer

Above-average reading ability.

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Question

Which side of the nature-nurture debate do the symptoms of Turner’s syndrome fall on? 

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Answer

The suggestion that chromosome patterns influence behavioural and physical characteristics suggests they fall on the nature side. 

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Question

What is a practical application of investigating these conditions?

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Answer

We can diagnose and treat these conditions early and effectively by investigating them.

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Question

What is a criticism of research into Turner’s syndrome and Klinefelter’s syndrome?

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Answer

Diagnosis of both syndromes assumes ‘typical’ gender behaviours. For example, stating that shy men are atypical suggests that confidence is a male characteristic, upholding societal views of a ‘typical male’. These assumptions could be problematic because the definitions of both syndromes use socially established gender norms to diagnose people with medical conditions.

Show question

Question

What is one environmental explanation for the behavioural characteristics associated with Turner’s syndrome?

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Answer

The social immaturity cited as a symptom of Turner’s syndrome could result from women with the condition being treated as younger than they are due to their youthful appearance. Looking young could lead to educational problems as teachers and parents may treat them as more immature and less educated than others. 

Show question

Question

Why do researchers state it is hard to generalise the 

findings of studies into Klinefelter’s and Turner’s syndrome? 

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Answer

Because the sample is very unusual compared to the 

general population.

Show question

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