Role of chromosomes and Hormones

• Chromosomes

  • Chromosomes are made of DNA.
  • We have 46 chromosomes, in 23 pairs, with the 23rd pair determining our biological sex.
  • Chromosomal structure for females is 'XX' and 'XY' for males.
• Chromosomes

  • All eggs (from the mother) have an 'X' chromosome and the sex is ultimately decided by whether the sperm is carrying an 'X' or 'Y' chromosome.
  • The 'y' chromosome carries a gene called the "Sex-determining region Y (SRY) which causes testes to develop -> causing the production of androgen's (male sex hormones).
• Hormones influence an individuals gender development.


  • Prenatally in the womb which involves brain development and the development of reproductive organs.
  • At puberty, a large burst of hormonal activity which triggers the development of secondary sexual characteristics such as pubic hair.
• A03

  Strength) Evidence for testosterone

  A condition called 'male hypogonadism' is caused by a mans testes failing to produce male sex hormones. A researcher gave 200 men w/ this condition hormone therapy and found that their muscle shape and sexual libido improved.

  -> This shows that testosterone has a direct influence on male sexual arousal, physical development in adulthood.
• A03

  Limitation) Reductionist

  These explanations reduce gender to just hormones and chromosomes and even underplay or ignore other explanations. For example, the cognitive approach focuses on the influence of thought processes such as our Schema.

  -> This suggests that gender is more complex than its biological influences alone.
• Testosterone

  • Controls the development of male sex organs during fetal development. If a genetic male produces no testosterone during the fetal stage, then no male sex organs appear. This is called an intersex condition.
  • Testosterone increases the size of the sexually dimorphic nucleus, a brain region that controls sexual behaviour. This region is typically larger in males than in females, which may be the reason why men have higher libidos.
  • High levels of testosterone are linked to aggression.
• Oestrogen

  • Female hormone that determines female sexual characteristics and menstruation.
  • Can cause heightening emotionally and irritability during menstrual cycle. (P.M.T/premenstrual syndrome)
• Oxytocin

  • Typically produced by women in much larger amounts, particularly as a result of birth. (causes the mothers to feel "in love" with their babies).
  • Stimulates lactation
  • Reduces stress hormone "cortisol" and facilitates bonding.
• A03

  Strength) A correlational study found a positive correlation between high testosterone and aggressive behaviours. For instance, studies have found that women who were exposed to testosterone before they were born displayed more manly behaviours.

  However, these studies are correlational and cannot establish cause and effect relationships.