Young children, reality, sex and gender

by Katie Alcock, Senior Lecturer in Psychology, Lancaster University

This essay was originally published on Medium on 29 May 2019

I’m a researcher in developmental psychology, and I’m interested in how young children learn symbols and how they think about the world. Most of my research is on children learning vocabulary but as a feminist (and mum of a boy and a girl) I’m also very interested in how children learn about sex and about stereotypes.

This is a rough summary of a talk I gave on April 27th in Lancaster as part of an event I and other members of For Women Lancashire organised entitled Gender Identity: Safeguarding Children and Young People. The talk itself was recorded and this isn’t a transcript, it’s more me writing up my notes and adding some thoughts.

I read Twitter a lot and I’ve come across this statement — that children who are “trans” knew they had a “gender identity” different to their biological sex when they were very young, 3, 4 years old — quite a lot.

For example, this tweet by Mermaids¹, a lobby group that advises families who think their child is trans (and only ever says YES your child IS trans), and trains schools (recently refusing to engage with a biology graduate school governor), quotes a study by psychologists at the University of Washington:


So, what exactly do these type of studies and quotes mean by “gender”, “sex”, “identity” etc.? What have psychologists found out about children’s developing knowledge of sex and gender?

Well, this research has been going on for a loooong time. All the studies I’m going to talk about are really robust — well replicated — this means that lots of researchers have found the same thing time and time again. We have known about some related aspects of children’s thinking since the 1920s or earlier and some of the main, older studies in this area are from the 1960s. This is not a flash in the pan.

What this also means is that terminology has changed. When this area of research first started, everyone knew, and was clear, that they were talking about children’s knowledge of biological sex. The terms “sex identity” and “sex constancy” were used, to mean children’s knowledge of whether they were a boy or a girl, and whether they or others could change into the opposite sex. Around the 1990s everyone started getting squeamish about the word “sex” and started using “gender” as a euphemism. Researchers, however, still meant a child’s knowledge of biological sex.

If you are geeky like me and want to see this change in terminology in a lovely graph, here you go.

The term “gender identity” has seen a steady rise over the last few decades, but while “sex identity” rose a bit at first, look at the dip in that term around 1980.

So researchers are clear that we are talking about children’s knowledge of sex, and that this can’t change. A nice quote from a 2003 paper:

“Categorical sex is an essential, immutable attribute of people that is maintained (by self and others) independent of changes in physical appearance (e.g., in hairstyle, clothes, or make-up) and of changes in behaviour (e.g., cross-sex play behaviour or homosexuality).”

(from Trautner et al., 2003, in the International Journal of Behavioral Development)

Nevertheless, it takes children some time to work out both whether they themselves are a girl or a boy, and that both they and others cannot change sex. Working out which they are themselves happens earlier, and is based in all the studies that have been done on physical appearance and stereotypes. Have a look at what James, aged 3, has to say on the matter:


James is firm that having short hair makes him a boy, and that it also makes other people (and dolls) into boys. My own child aged four was convinced a teenager we knew must be a boy because she had short hair.

This just in— India Willoughby also thinks women with short hair are somehow different. Perhaps India is also 3?

Now these days we are all anti-stereotyping and we are convinced we have not raised our children to know what sex stereotypes are. If the only influences on children were things people said directly to them, and especially things we as parents said directly to them, this might work out. But children don’t grow up in a vacuum — they see the other children at nursery, they see toys that other children play with, obviously they hear what other adults than their parents say but most of what children take in is not from people talking to them, but from what they see.

Making generalisations is a very useful skill for a baby or child — if they couldn’t make generalisations, they would never be able to work out that a new cat they saw was in fact a cat, or a new apple was just as good to eat as the last one, or a new car is likely also to go places. Children can work out at a very young age that there are men and women, boys and girls, in the world — it’s probably quite useful for them to work this out in the general scheme of things².

So when they see all the girls at nursery wearing pink and having long hair, well, that’s what girls do! And they also realise, from what people are saying, and from how their parents dress them, what toys they are given, and what toys other children who look like them (same clothes, same hair) what they are supposed to like and do based on what sex they are.³

If you’re interested in reading more about how insidious gender stereotypes are in children’s worlds, you could do much worse than read pretty much the whole website at Let Toys Be Toys.

So, based on the idea that girls have long hair and boys have short hair, James is also age-perfect in thinking that when appearance changes, sex changes too. Until the age of about 7 (yes, 7 — in some children it’s older) children think that when something changes its appearance, its underlying reality changes too. This doesn’t just apply to sex, it applies to pretty much everything. 

To show you what I mean, have a look at this little girl who was asked about what people think is in a pot, when she knows it’s got pennies instead of playdough. This adds another layer to the issue where she has to think about not just what is real but what another person knows — also something that children are really bad at during these ages. But basically, we can see (and again, it’s REALLY easy to get kids to do this for you) that she thinks because she knows what’s really in it, then “what’s really in it” is now obvious to everyone else too.

I couldn’t find a good video but the next picture shows the kinds of things we can use to check children’s understanding. We would show children one of these toys — a candle that looks like a crayon or a banana that looks like a pen — and ask them what it is. “It’s a banana!” they would say. Does it look like a banana? Yes! Is it really a banana? Yes!

Until, that is, they realise it’s actually a pen, when they would say that it looks like a pen, and it really is a pen, and usually also that they always thought it was a pen. You can also convince children that a cat in a dog mask is really a dog, and has always really been a dog.

By the time children are about 6 or 7 they are getting better at understanding that objects don’t change their real essence when they change their appearance but they still think that people change their sex when they change their appearance — this is known as sex (or gender, if you’re squeamish) constancy. In this next video the 5 year old, like James above, thinks carrying a handbag makes the doll into a girl and the 9 year old is struggling not to say DOH.

But at the same time — we’re talking 4, 5, 6 and even 7 — children do NOT understand that people’s genitals (and biology in general, but genitals are more obvious to small children) are what makes them boys or girls, men or women. Researchers think that earlier knowledge about biological differences between men and women does help children to understand at a younger age that people cannot change sex.

But it isn’t a complete answer — some children can understand that men have penises and women have vaginas, but still think that changing clothing makes a girl into a boy, if they also think that a cat wearing a dog mask has become a dog. In other words, to get to a mature understanding of sex constancy you need to understand what makes a boy and a girl, biologically, and also understand that the underlying essence of a thing isn’t dependent on its appearance.

Now we come to the present day and the transgender agenda. Parents are, by and large, reasonably happy for their children to do things that are outside the range of what’s generally in the “allowed” stereotypes for their sex. That is to say, mums are happy whatever their children do and dads are happy for their girls to do “boy” things. Dads are much less happy for their boys to do “girl” things or wear “girl” clothes. This is 100% no doubt linked to the devaluing of things to do with women — lower pay, lesser status, “run like a girl” is an insult, “man up” a positive suggestion.

But of course children have their own preferences and influences and they like doing what they like doing even if that happens to be something their parents think isn’t “right” for their sex. It’s called personality. So, even when children realise that boys are “supposed” to like cars and wear jeans and have short hair, they may not actually want to do that if they are a boy.

So we now have children like “Lily”, here shown on the Victoria Derbyshire programme. Lily is 6. Six year olds think that if you change your clothes, you change sex. Lily therefore thinks that putting on a dress makes you into a girl. Literally makes you into a girl. Not “means your inner gender essence is a girl”. Literally changes your sex.

So, if we go back to the study that Mermaids quote above⁴, on young children “knowing what their gender identity was” — let’s unpack that a bit more.

Children know what they like. When society and the world tells them that the things they like are those that boys like — but they have been told in words that they are a girl — well, that’s easy. They already know that having short hair makes you into a boy. They know that playing with cars makes you into a boy. So it’s easy! Boy all the way. And their version of the world, at their age, means that changing sex is totally possible.


[1] I don’t want to make this piece a “reply to Mermaids”. But as they tend to come out with pieces of information that are relevant to child development, it makes sense to note what they say and why it’s relevant, or not.

[2]Mermaids also point this out in this piece.  It’s helpful to know as it does tell us the first steps in children associating stereotypes with men/women/boys/girls.

[3] Mermaids also acknowledge this in the same piece.

[4] This is the same article that Mermaids quote in the same Mail on Sunday reply piece. I don’t know if there are other studies on gender-non-conforming children that do or do not find the same, that I haven’t come across, or if this is basically it.