A person's biological sex is determined at the time of concetion by the father's sperm. In the 6th week of pre-natal development the Y chromosome produces a protein which causes th undifferentiated gonads to become testes and sets the path of male development of the feotus. if the protein is not resent the gonads develpop into ovaries.
Once the gonads have developed, further sexual development and sex differences are triggered by hormones.Pre-natally it is thought tat testosterone and dihydrotestosterone influence the brain. Research suggests that they make the sexually dimorphic nucleus twice as large in males compared to females. other research suggests that testosterone slows down the development of sme parts of the brain while speeding up other- such as the right hemisphere. This may explain why men are better at spatial tasks and women better at verbal ones.
- Females exposed to high levels of testosterone in the womb show more tomboish behaviouor and rough and tumble play than females that haven't been exposed. This tells us that hormones affect behaviour as high levels of testosterone lead to a masculine bhavior in this case.
- Rats that were injected testosterone while pregnant gave birth to female rats that had male like genitals and they attempted to mate with oter female rats. In this same study it was found that the female offspring had a sexually dismorphic nucleus the size of a male rat. It was found on monkeys that were exposed to male hormones in their pre-natal development that they tended to show more rough and tumble play compared to a group of monkeys not exposed to the hormones. This shows us that testosterone does affect gender identity,appearence and behaviour.
- The evidence from the Batista family demonstrates that genetics and hormones affect gender identity and development as the men took on male roles after being physically changed into a man, supporting the theory that testosterone has a profound influence on gender identity.
- Devid Reimer's case tells us that nature impacts our gender identity, he never came to terms to being a female becase what happens pre-natally overrides what happens post-natally as our biological sex imnluences our gender identity.
Issues Debates and Approaches
REDUCTIONISM- saying that gender development is enterily down to genes and hormones is reductionist because gender develoment is a complex issue that lasts well beyond birth. So this approach is too simple: social and cognitive factos surely play a role in gender development so this explanation reduces complex human experiences down to genes and chemicals.
APPLICATIONS- It leads to the biological treatment of gender disorders instead of attempting to realign gender through cognitive help.