Biological sex is determined by chromosomes in your genes. At prenatal development, only a few weeks after conception, there is no notable difference between male and female structure until the Gonadal Ridges, the structure which develops either female or male sex organs, grows to determine the sex of the baby. All prenatal babies have genitalia that appears distinctly feminine until at three months, hormones- testosterone if the baby’s to be a boy, and oestrogen if the baby’s to be a girl- is released and the baby develops into the hormone determined gender. For these reasons it is believed that there is a direct link between chromosomes and sex, and therefore sex and gender behaviour.
Biology can be used to explain a person’s gender using hormones and genes as a reason for gender behaviour, because hormones influence both genitalia and brain development which then influence the development of gender behaviour. This could explain why some girls and women become tom boys, perhaps due to too much exposure to testosterone during pre natal and adolescent development which masculinises the brain so that they display male gender behaviour; meaning a female may display the more masculine trait of spatial skills as the testosterone acts on this cerebral of the brain. A supporting hypothesis for this theory is Geswind & Galaburda (1987) who were the first to propose that sex differences are caused by the effects of testosterone levels on a developing brain. Research by Deady et al has demonstrated that this hypothesis may be correct; he found that high levels of salivary testosterone in biological females were linked with low scores of maternal personality. This study helps in supporting that hormones have a great influence on the development of gender behaviour, and that certain hormones can determine gender traits.
This approach to gender development sits on the nature side of the nature vs.