• The Role of Genes – A persons biological sex is determined at the time of the conception by the fathers sperm. If the egg is to develop into a female, the father will contribute the X gene (**) and if a male, the father will contribute the Y gene (XY). The other X chromosome is from the mothers egg. Up until 6 weeks, all foetuses have the same gonads, these then develop into ovaries or testes. In the 6th week of pre-natal development, the Y chromosome produces a protein which causes the gonads to become testes. If the protein doesn’t occur due to not having a Y chromosome, the gonads become ovaries.
• The Role of Hormones – Once the gonads have developed, hormones kick in. If testes are present, testosterone & dihydrotestosterone is released and the Wolffian Sytem develops further. If the androgens are not present, the Mullerian System develops. It is thought that this part of development is crucial for gender development as it then influences puberty later on in life. Research suggests that males have a larger SDN (sexually dimorphic nucleus) which can slow down parts of the brain, making women better at some things than men and vise versa.
David Reimer Case Study:Born male, aged 22 moths when his circumcision went wrong, his penis was turned into a vagina and he was encouraged to become female (Dr. Money). When he was 14 he learned what happened to him, he never felt right as a female. Had sex reassignment surgery to turn him back to being male. This study shows that genes and hormones do mean something as he never felt female even though he was nurtured to be. Even as a foetus, the gender development in the womb which made him male, made him biologically male for life. This suggests that gender is more than just the way you have been brought up and nurtured. However, we cannot generalise as this is a case study, it may be different for someone else. There are some variables that cannot be changed such as the male nurturing he had up to 22 months, this may have had an effect.
Diamond:Injected pregnant rats with testosterone; the female offspring had male like genitalia and they attempted to mate with other female rats: acting male due to the increase of testosterone? Hormone influence?
Young:Showed that female monkeys who were exposed to testosterone in the womb (in a similar way to diamond) tended to engage in rough and tumble play compared to a control group of other female monkeys with no testosterone manipulation. These pieces of research suggest that the change of the size of the SDN makes the animals act more masculine, showing that nature has more of an effect than nurture.
The use of animals is unethical as they are not protected