Parents hold hand with their toddler child whilst going up steps

Gender source

Are differences in behaviour between males and females biologically based or do they reflect cultural influences?

Usually, a person’s sex is quite clearly biologically defined. But your gender will not be so straightforward. Gender qualities vary across individuals of both sexes rather than neatly falling into one of two categories. Many factors other than genes will affect these qualities, such as the behaviour of parents and friends, school environment, social attitudes and so on.

This is the long-standing nature–nurture debate. Like most other human characteristics, sex and gender differences are likely to reflect a complex interplay between genes, hormones and environment.

Ignoring this complexity has obvious dangers. If differences are viewed as innate, they may be seen as unchangeable or force people to behave in a particular way – or promote unhelpful stereotyping. But ignoring biological reality when dealing with social issues could also be unproductive.

Upbringing versus biology

Do gender-specific behaviours arise in children because of biological factors, or because infants are encouraged (consciously or subconsciously) to conform to particular gender roles?

Between the ages of one to two years most children begin to display gender-specific behaviours. Boys will tend to choose vehicles or construction toys to play with; girls go for dolls. These behaviours appear so early that some suggest that they must be innate, while others argue that they simply reflect parental influences or the child’s desire to conform.

The possible causes are difficult to study. With human subjects, controlled studies cannot be carried out to compare the impact of, say, prenatal hormones or particular styles of parenting.

Observational studies suggest that parents tend to treat male and female children differently from birth, even without realising it.

On the other hand, girls with congenital adrenal hyperplasia (CAH) – who have relatively high testosterone levels – are typically said to be more ‘tomboyish’ than other girls. Early in life they also show greater preference for ‘male’ toys. Such studies argue in favour of a biological influence mediated through hormones.

Are these preferences mirrored in animals? Studies in rats have shown sex-specific behaviours, but these disappear if the effect of sex hormones before birth is blocked. A 2008 study in primates showed boy monkeys preferred wheeled vehicle toys to soft animal toys, while girl monkeys were less choosy. Although primates may have social structures, this is more likely to reflect some level of innate preference.

One way to tease apart cultural/environmental and genetic/biological influences is through twin studies. By comparing characteristics in identical twins (which share all their genes) and non-identical twins (which share half their genes), researchers can estimate the relative contributions of genes and environment, though such studies do not say anything about what these influences actually are.

In one infamous case a psychologist at Johns Hopkins University in Baltimore persuaded the parents of a pair of twins to bring up their son as a girl after his genitals were mutilated in a circumcision operation. The psychologist, Dr John Money, was trying to prove that gender is strongly influenced by environmental factors. But 25 years after Money’s report was published in a scientific journal, it emerged that the child (Bruce Reimer) had learned the truth and reclaimed his biological sex as a teenager, having never felt comfortable living as girl.

Lead image:

Kat Grigg/Flickr CC BY


Questions for discussion

  • In the genes or in the papers – where do you think the source of gender difference comes from?

Further reading

About this resource

This resource was first published in ‘Sex and Gender’ in January 2006 and reviewed and updated in October 2014.

Genetics and genomics, Ecology and environment, Psychology
Sex and Gender
Education levels:
14–16, 16–19, Continuing professional development