The following study will aim to show how chromosomes have a more powerful influence on gender than experiences. However environmental factors may also have an influence. You must explain this in an essay. Imperato McGinley et al (1974) The Batista family Imperato-McGinley and her colleagues studied some unusual families including the Batista family from three villages in the Dominican Republic. Thirty seven children studied by the researchers had inherited a mutant recessive gene from an eighteenth century ancestor. They were born with apparently female genitals and were brought up as girls even though they all had XY chromosomes. When they reached puberty, the surge in testosterone levels, led to the production of a male hormone (dihydrotestosterone) which they had lacked before birth. This hormone led to their rather belated masculinisation and the sudden development of male genitals. They were born with normal female genitalia and body shape, but when they were twelve, their vaginas healed over, two testicles descended and they grew full penises. So the little ‘girls’ grew up to be muscular men. Curiously these people reported no difficulty in adopting the male gender despite being reared as girls. They adapt their new gender identity well to their new sex, take men’s jobs, marry women and are treated as men by others. So the role of socialisation in the development of sex roles appeared to be overridden by biological factors and the researchers concluded that biology was all important. Their ability to adopt a male gender identity and gender role suggests that their testosterone had preprogrammed masculinity into their brains. However, one problem with this study was that the genitalia of these ‘female’ children were not entirely normal and others knew this from communal river bathing. It may be that the rearing of these children was not the same as that of normal females, especially as villagers would have known of other children with this disorder. It is also possible that the young men had no difficulty in adjusting to their new gender because they had always been uncomfortable with the female role. Certainly they were given support by their community to make the transition. This clearly suggests environmental influences on the children’s gender identity. Evidence that hormones (biology) have an effect on an individual’s gender related behaviour. Congenital adrenal hyperplasia (CAH) The psychological effects of testosterone can be seen in a condition called congenital adrenal hyperplasia (CAH). It is a rare condition which can affect both males and females. It causes heightened levels of male hormones. Genetic females XX with the condition are often described as tomboys, have higher levels of aggression than other girls, prefer male toys and show superior ability in spatial tasks (Berenbaum and Hines, 1992). However, studies of aggression in girls with CAH have so far yielded inconsistent results. Hines (2004) reports a number of studies comparing aggression levels between CAH girls, CAH males and controls using various measures of aggression. Some of these studies show significant effects while others show no differences. Most CAH research involves small samples. Lab studies with animals tend to show that testosterone does lead to increased aggression. A study to support the fact that gender is a result of both genes and environment. Mr Blackwell: Hermaphrodite (Goldwyn, 1979) Goldwyn cites the case of Mr Blackwell, only the 303 rd true hermaphrodite in all of medical history (where person’s cells are both female XX and male XY). He’s described as a handsome and rather shy 18 yr old boy. Although he had a small vaginal opening as well as a penis, he was taken to be a boy and brought up as such. But when he was 14yrs he developed breasts and was sent to hospital to discover why this had happened. It was found that he had an active ovary on one side of his body and an active testicle on the other. Gross (1987) suggested that in fact he could well be said to have a ‘female brain’ for his hormone system was enough to take him through the whole female cycle and ovulate every month. Nevertheless, he expressed his wish to remain male and so his female parts were removed. His upbringing as a male seems to have been a major influence on gender development. This case then underlines the strength of nurture, since his upbringing as a boy influenced his gender identity as a male, OVERIDDING his female bio chemistry. Also the surgeon who had carried out the operation on Mr Blackwell, and on 25 other similar cases – all these people had no doubt about their gender, which was always in line to how they were raised – male or female. It therefore seems that biology alone can not determine gender development.