Chromosomes and Hormones

• Chromosomes

  Humans have 46 chromosomes made from DNA (23 from the mother and 23 from the father) of which the last pair determine a persons biological sex. Females have an XX chromosome while males have XY chromosomes. The Y chromosome carries a gene called the sex determining region (SRY) which is what causes testes to develop in the XY embryo to produce male sex hormones known as androgens and therefore causes the embryo to become male. Without this the embryo will develop into a female.

   

   
• Hormones

  Hormones are the main influence for finding gender development. In the womb, hormones act upon brain development and cause development of reproductive organs. During puberty, a burst of hormonal activity causes the development of secondary sexual characteristics such as pubic hair.

   
• Testosterone

   

  Testosterone is a male hormone which controls the development of male sex organs from around 8 weeks of foetal development and is often related to aggressive behaviour. Human and animal studies have shown the influence of increased testosterone on aggressive behaviour. Van de Poll et al carried out a study which showed that when female rats were injected with testosterone they became more physically and sexually aggressive.

   

   
• Oestrogen

  Oestrogen is the female sex hormone which is responsible for determining female sexual characteristics and menstruation. It may cause some women to experience heightened emotions and irritability when menstruating which is known as pre menstrual syndrome (PMS).

   
• Oxytocin

  Oxytocin is the love hormone produced by males and females however women often produce more of it. Levels of oxytocin can be increased through kissing, hugging and women giving birth etc which also decreases cortisol which is the stress hormone.
• Strength: Case study

  There was a case study where David was born as Bruce and was circumcised as an infant where his penis was accidentally burnt off. A psychologist worked with his parents and suggested that he should be renamed and Brenda and raised as a girl as gender is created entirely by environment. When Brenda found out due to her feeling suicidal and being told the truth she changed back to living as a man and renamed himself as David. This shows that biology plays a big influence on our gender and not socialisation. Therefore, gender can’t be easily influenced through environment.
• Strength: research support

  Dabbs et al studied studied prison populations and found that offenders with the highest levels of testosterone were more likely to have committed violent or sexually motivated crimes. Van Goozen et al’s research also supports the role of chromosomes and hormones. They studied transgender people who were going through hormone treatment and being injected with hormones of the opposite sex. They found transgender women showed a decrease in aggressive behaviour while transgender men showed an increase

   
• Limitation: alternate explanations

  Ignores alternate explanations. Psychologists argue that the cognitive approach would be a better explanation as it draws attention to the changing thought processes the underpin gender development. Although the biological models acknowledge the importance of innate factors, the psychodynamic approach would also point to the importance of childhood experiences such as interactions in the family. Therefore, the biological approach may be a weakness as it is reductionist and ignores other factors which a holistic approach may explain better.