biological explanations

• role of chromosomes = carries genetic information from parents to offspring
• Y chromosomes are the sex determining chromosomes allowing testes develop in the uterus
• androgens cause the embryo to become male
• What time are testes developed allowing production of testosterone?

  3 months
• What is testosterone?

  hormone that stimulates secondary male characteristics
• Testosterone

  • Affects brain development prenatally and during puberty
  • Causes a surge immediately after birth impacting sex organs development and hypothalamus in the brain
  • Impacts brain areas linked to spatial skills, competitiveness, and aggressiveness
• Oestrogen


  • Steroid hormones that promote development and maintenance of female characteristics in the body
  • Plays a part in puberty promoting sexual characteristics and menstrual cycle
  • No effect in women and do not need hormones to direct prenatal genital development
• Oxytocin


  1. Acts as a neurotransmitter controlling a key aspect of the reproductive system

  2. Produced by both men and women

  3. In combination with oestrogen, helps with contractions and stimulating breastfeeding

  4. Promotes intimacy during sex increasing up to 5 times

  5. Believed to affect females' social behavior such as mate selection and nesting behavior
• Research supports the determining influence of chromosomes on gender identity


  • For example, the case of David Reimer showed the influence of XY chromosomes on gender identification despite being raised as a girl
  • Case studies by Bradley et al (1998) and David Reimer suggest that nature (chromosomes) has a stronger influence than nurture on gender identity
  • Both cases demonstrate abnormal development, making it difficult to generalize to normal sex and gender development
• Case studies are hard to generalize to the wider population, making evidence weak to support the role of chromosomes in gender development
• Wang's research showed that testosterone treatment improved sexual function, libido, and muscle strength in males with hypogonadism, indicating a direct influence of testosterone on sexual arousal
• O'Connor's study on increased testosterone levels in healthy young men found no significant increase in sexual behavior, suggesting hormones affect gendered behavior more in individuals lacking testosterone than in those with normal levels
• The reductionist approach to biological explanation of gender development breaks down behavior to the lowest level of reductionism, focusing on factors like the SRY gene, testosterone, oestrogen, and oxytocin
• The reductionist approach ignores external influences on behavior such as the environment, suggesting a more holistic approach considering cognitive and environmental factors is needed for a complete explanation
• Klinefelter's Syndrome affects 1 in 600 males
• Klinefelter's Syndrome


  Chromosome structure of XXY
• Physical Symptoms of Klinefelter's Syndrome

  • Poor beard growth
  • Breast development (gynecomastia) and underdeveloped testes
  • Rounded body contours
  • Long gangly limbs
  • Problems with coordination/clumsiness
• Psychological characteristics of Klinefelter's Syndrome

  • Poorly developed language skills and reading ability
  • Passive, shy, lack in sexual activity
  • Respond badly in exhibit problems in memory and problem solving
• Psychologists study people with Klinefelter's Syndrome for comparison with typical sex chromosomes and to infer biological basis regarding gender development
• Turner's Syndrome affects 1 in 5000 females
• Turner's Syndrome

  Absence of X chromosome = XO
• Turner's Syndrome

  45 chromosomes instead of 46
• Physical characteristics of Turner's Syndrome

  • Webbed neck
  • Low set ears
  • Low hairline
  • Lack of pubic hair
  • Bicuspid aortic valve
  • Ovarian dysgenesis
  • Shielded chest
  • High waist to hip ratio
• Psychological characteristic of Turner's Syndrome

  • Higher average reading ability
  • Spatial/visual memory lower than normal
  • Trouble relating to peers
  • Finding it difficult to fit in
• Turner's Syndrome is treated with oestrogen
• Strength: 'Studying atypical chromosome patterns contributes to our understanding of the nature-nurture debate in gender development'
• Strength: 'Practical application in studying atypical chromosome patterns increases understanding of the syndromes, leading to earlier diagnosis and targeted psychological deficits for improved quality of life'
• Weakness: 'Caution should be exercised when making conclusions based on limited and unusual samples'
• Weakness: 'It may be hasty to attribute differences solely to biology without considering possible environmental explanations'