What does it mean to be female? When we ask people this question, they all have an answer to it, in some form or another. And in some ways, we all know that the answer will depend on every individual's particular context or place in the world and, indeed, their age.

But never has there been a time when the question of sex or gender is more in play. Some people do not wish to describe their gender as female or male. We need to understand the meaning of new terms like ‘gender fluidity’ where a person likes to describe themselves as a mix of girl and boy, identifying differently depending on time and place.

By contrast perhaps, asexuality is used to describe a state in which sexual orientation is characterised by a persistent lack of sexual attraction towards any gender.

Given this change in the landscape from a simple binary idea of being female or being male, and of gender or sexual identity, you may well ask how we can poduce a book entitled The Female Mind with any degree of confidence.

We now know that being female is a very active process. In all mammals, the developing brain becomes actively masculinised so that the adult brain and adult reproductive behaviour are consistent with each other and with the sex cells (differentiated gonads) of the individual body. And although brain is thought of as being ‘destined to be female’ unless exposed to male hormones (testosterone) during pregnancy, we are now discovering that becoming female is not just a passive result of not having testes and not being exposed to testosterone. In fact, being female is a very active process indeed. To be female, the ‘male genetic programme’ has to be actively suppressed in females by a female-specific pattern of switching genes on and off by a process called methylation. Even more surprising perhaps, this brain feminisation is maintained by active suppression of masculinisation throughout life. More recent work suggests that this process can be influenced by a range of environmental effects (e.g. smoking/nutritional/ stress) to a greater or lesser extent.