We hear people talking about ‘sex’ and ‘gender’ all the time but what do they really mean? Do they mean the same as they always have?

Estimated reading time: 5 minutes

The meaning of words frequently changes over time and words mean different things to different generations or different cultures. A good example of this is the word ‘sick’– to me it means someone is unwell or means a pile of vomit. However, to my teenagers it means something is impressive or attractive!

Biological Sex

Until quite recently the words sex and gender were used interchangeably to mean someone’s biological sex. Someone’s biological sex is determined at conception. The moment that a sperm fertilises an egg the sex of the developing baby is decided. A sperm with a Y chromosome combined with an egg (which always has an X chromosome) will be a male child. In the same way a sperm with an X chromosome combined with an egg will be a female child. There are some rare disorders where there are missing or extra chromosomes, but basically the presence or absence of a Y chromosome determines whether a baby is male or female. It is the X and Y chromosomes that then determine what reproductive organs the baby develops (there are a few very rare medical disorders where this can go wrong).

Some parents like to know the sex of their baby before it is born and the sonographer can usually tell by looking at the genitalia when they do an ultrasound scan. If the parents decide not to find out before the baby is born, then there is great excitement at birth as everyone asks “is it a boy or a girl?”. The midwife looks at the baby’s genitalia and in the vast majority of cases it is very easy to see whether the baby is male or female.

Biological sex then is determined by chromosomes at conception and observed at a scan or at birth.


Until recently when a person was asked their gender on a form, what it actually meant was their biological sex. This is important especially in medical records because many illnesses affect males and females differently. However a change in how society understands the word gender leads to endless confusion!

Gender is now commonly understood to mean the characteristics of women, men, girls and boys that are socially constructed (World Health Organisation’s definition). That means that gender is being understood in terms of what a person does, how they behave, how they dress, etc., rather than their biological sex.


This definition of gender also means that people have begun to identify as a gender which is not the same as their biological sex, particularly if they do not fit society’s view of what a person of their sex should be like. Hence the term ‘gender identity’ which is defined as a person’s internal sense of whether they are male or female, both or neither. Just to make things even more complicated people also talk about gender expression which is defined as a persons behaviour, mannerisms, interests and appearance that are associated with categories of femininity and masculinity.

So you can see that initially the terms sex and gender meant basically the same thing – biological sex based on chromosomes and observed in reproductive organs. However, in our society currently they mean different things. Biological sex cannot be changed regardless of how a person might see themselves or how they might behave or dress.

As Christians our understanding of who we are comes not from inside ourselves but from God who created us. He created each us male or female, this was determined at conception and is unchangeable.

So God created man in his own image, in the image of God he created him; male and female he created them.

Genesis 1:27


For you formed my inward parts; you knitted me together in my mother’s womb. I praise you, for I am fearfully and wonderfully made. Wonderful are your works; my soul knows it very well. My frame was not hidden from you, when I was being made in secret, intricately woven in the depths of the earth. Your eyes saw my unformed substance; in your book were written, every one of them, the days that were formed for me, when as yet there was none of them.

Psalm 139: 13 – 16