The role of chromosomes and hormones (testosterone, ostrogen and oxytocin) in sex and gender. Atypical sex chromosome patterns: Klinefelter's syndrome and Turner's syndrome.

What Determines Biological Sex?

• Biological sex is determined by chromosomes.
• Humans normally have 23 pairs of chromosomes, including one pair of sex chromosomes.

What are Sex Chromosomes?

• Chromosomes that determine biological sex.
• Females typically have XX chromosomes and males typically have XY chromosomes.

What is the SRY Gene?

• SRY stands for Sex-determining Region Y.
• Found on the Y chromosome.
• Triggers male development.

How does the SRY Gene Determine Biological Sex?

• SRY gene triggers the development of testes.
• Testes produce testosterone.
• Testosterone leads to male development.

What Happens When the SRY Gene is Absent?

• Testes do not develop.
• Female development occurs.

What is Testosterone?

• Male sex hormone (androgen).
• Produced mainly by the testes.
• Present in both sexes but at higher levels in males.

What is the Role of Testosterone in Physical Development?

• Promotes development of male secondary sexual characteristics.
• Includes facial hair, deeper voice and increased muscle mass.

What is the Role of Testosterone in Gender Development?

• Associated with aggression.
• Associated with competitiveness.
• Associated with dominance and risk-taking behaviour.

What is Oestrogen?

• Female sex hormone.
• Produced mainly by the ovaries.
• Present in both sexes but at higher levels in females.

What is the Role of Oestrogen in Physical Development?

• Promotes development of female reproductive characteristics.
• Influences menstrual cycle and fertility.

What is the Role of Oestrogen in Gender Development?

• Associated with nurturing behaviour.
• Associated with emotional sensitivity.
• Associated with feminine gender-role characteristics.

What is Oxytocin?

• Hormone produced by the hypothalamus.
• Released by the pituitary gland.
• Sometimes called the “love hormone”.

What is the Role of Oxytocin in Gender Development?

• Promotes attachment and bonding.
• Associated with trust and social relationships.
• Associated with nurturing and caregiving behaviour.

Why is Oxytocin Important in Females?

• Released during childbirth and breastfeeding.
• May contribute to maternal behaviour and attachment.

What are Atypical Sex Chromosome Patterns?

• Unusual combinations of sex chromosomes.
• Can affect physical and psychological development.

What is Klinefelter’s Syndrome?

• Genetic condition affecting males.
• Caused by an extra X chromosome.
• Chromosome pattern is XXY.

What Causes Klinefelter’s Syndrome?

• Presence of an additional X chromosome.
• Results in an XXY chromosome pattern.

What are the Physical Characteristics of Klinefelter’s Syndrome?

• Sparse body hair.
• Poor muscle development.
• Broader hips.
• Infertility.

What are the Cognitive Characteristics of Klinefelter’s Syndrome?

• Poor language skills.
• Difficulties with reading.
• Lower verbal intelligence.

What are the Behavioural Characteristics of Klinefelter’s Syndrome?

• Shy personality.
• Passive personality.
• Less assertive behaviour.

Why does Klinefelter’s Syndrome Support Biological Explanations of Gender?

• Chromosome abnormalities are associated with behavioural differences.
• Suggests chromosomes influence gender development.

What is Turner’s Syndrome?

• Genetic condition affecting females.
• Caused by the absence of one X chromosome.
• Chromosome pattern is XO.

What Causes Turner’s Syndrome?

• One X chromosome is missing.
• Results in an XO chromosome pattern.

What are the Physical Characteristics of Turner’s Syndrome?

• Short stature.
• Broad chest.
• Infertility.
• Underdeveloped ovaries.

What are the Cognitive Characteristics of Turner’s Syndrome?

• Higher verbal ability.
• Difficulties with spatial tasks.
• Difficulties with mathematical tasks.

What are the Behavioural Characteristics of Turner’s Syndrome?

• Social immaturity.
• Difficulties in social relationships.

Why does Turner’s Syndrome Support Biological Explanations of Gender?

• Chromosome abnormalities are associated with behavioural differences.
• Suggests chromosomes influence gender development.

Who was David Reimer?

• Male who was raised as a female following a medical accident.
• Studied by Money et al.

Money et al. — Aim

• Investigate whether gender identity is determined by biology or socialisation.

Money et al. — Procedure

• David Reimer was raised as a girl after a medical accident.
• Parents encouraged female socialisation and gender-role behaviour.

Money et al. — Findings

• David never identified as female.
• Eventually returned to living as a male.

Money et al. — Conclusion

• Suggests biological factors influence gender identity.
• Challenges the idea that gender is solely learned through socialisation.

Chromosomal Explanation Evaluation — Research Support

• Klinefelter’s and Turner’s syndromes are associated with consistent behavioural characteristics.
• Supports the role of chromosomes in gender development.

Why does Research Support Strengthen Chromosomal Explanations?

• Behavioural differences are linked to chromosome abnormalities.
• Suggests chromosomes influence gender-related behaviour.

Chromosomal Explanation Evaluation — Real World Evidence

• Klinefelter’s and Turner’s syndromes occur naturally.
• Provide evidence from real-life chromosome variations.

Why does Real World Evidence Strengthen Chromosomal Explanations?

• Demonstrates the effects of chromosome differences outside laboratory settings.
• Increases ecological validity.

Chromosomal Explanation Evaluation — Individual Differences

• Not everyone with Klinefelter’s or Turner’s syndrome shows the same characteristics.
• Symptoms vary considerably between individuals.

Why do Individual Differences Weaken Chromosomal Explanations?

• Chromosomes cannot fully explain gender-related behaviour.
• Other biological and environmental factors may be involved.

Chromosomal Explanation Evaluation — Reductionism

• Focuses mainly on chromosomes and hormones.
• May ignore social and cultural influences on gender.

Why does Reductionism Weaken Chromosomal Explanations?

• Gender development is likely influenced by both biological and environmental factors.
• Biological explanations may oversimplify gender development.

Chromosomal Explanation Evaluation — Determinism

• Suggests gender is biologically predetermined.
• Leaves little room for free will and personal choice.

Why does Determinism Weaken Chromosomal Explanations?

• Individuals may actively shape their gender identity.
• Biological explanations may underestimate personal agency.

What Nature-Nurture Position do Chromosomal Explanations Support?

• Strongly support the nature side of the debate.
• Emphasise biological influences on gender development.

Why is an Interactionist View of Gender Development More Realistic?

• Gender is influenced by both biology and environment.
• Chromosomes, hormones, socialisation and culture all contribute to gender development.