<i></i>

Photo: Getty Images

You don't get far in this whole pregnancy and children thing before someone explains to you the difference between boys and girls. And no, not just the obvious. Barely a day goes by without someone telling you there are "innate" differences between the genders.

Typically the proof for this startling piece of knowledge is someone was talking to someone who watched a YouTube clip featuring someone who'd read an article on the internet that showed women are hardwired to prefer pink to other colours.

And with evidence like that, who am I to argue?

Gender reveal cake ... The baker is given the ultrasound result and proceeds to prepare a pink or blue cake with white icing.

Gender reveal cake ... The baker is given the ultrasound result and proceeds to prepare a pink or blue cake with white icing. Photo: Baby Bird Art, via parentsociety.com

In fact, as the mother of the most girly three-year-old imaginable, I too have relied on inherent gender differences to explain why my daughter likes to colour in pictures of fairies while my friend's son of a similar age prefers to commando-roll off the couch.

But my recent discovery of "gender reveal parties" has made me wonder how many of these "hard-wired" gender differences are actually just social constructs.

As the name suggests, gender reveal parties are occasions at which expectant parents "reveal" the gender of their in utero foetus to family and friends. And you know that this is an important phenomenon, because there's a whole Pinterest category devoted to it.

Gender reveal party ideas on Pinterest.

Gender reveal party ideas on Pinterest. Photo: Sammy Berube via Jennifer Tomasella, Pinterest

For the uninitiated, gender reveal parties go something like this: at the ultrasound the doctor is asked to seal the results in an envelope. The envelope is then given to a baker who prepares a cake with white icing. In the presence of their nearest and dearest, the parents-to-be cut the cake to reveal a coloured cake inside. If the cake is pink then it's a girl. If it's blue then everyone present knows that they best bring superhero bibs instead of princess dolls to the baby shower.

There are variations on the type of reveals. On Australia's BabyCentre website one pregnant woman writes about asking a party shop to fill a box with either pink or blue balloons.

Aside from being yet another way to turn yet another part of parenthood into a mega-sale opportunity, gender reveal parties show just how wedded we are to gender stereotypes. Even before kids are born we're treating them differently and imposing cultural norms on them — even down to their preferred colour.

No doubt, girls do prefer pink. My three-year old certainly does, despite my best efforts to widen her colour palette. But is it any wonder given there is a whole culture set up to impose these stereotypes?

And colour stereotypes are indeed culturally imposed. Prior to the 20th century children were as likely to be dressed in white as any other colour. If anything, boys were dressed in pink and girls were in blue.

Just look at the 1953 version of Disney's classic animation Peter Pan. Michael, the youngest child, is dressed throughout the movie in a pink onesie. Disney has nevertheless made amends for its subversive transgression by re-colouring Michael's suit blue on the cover of the recent DVD release.

Imposing gender stereotypes on the yet-to-be-born goes beyond colour preferences. In her 1986 book about the then new practice of amniocentesis, The Tentative Pregnancy, sociologist Barbara Katz Rothman asked 120 pregnant women about their babies' foetal activity.

Women who knew they were pregnant with girls described the foetal movements as "gentle", "quiet" "rolling" and "moderate, reassuring but not violent". Those with boys likened their foetus' movements to "kicks", "constant jabbing", and "a saga of earthquakes".

A control group, who didn't know the sex of their babies, did not use similar gendered language in the descriptions of their babies' movements.

Why does any of this matter? Because these stereotypes that we impose continue to follow us through adulthood.

Gender scholar Deborah Siegel argues that less-gendered childhoods lead to greater gender equality in adulthood.

"Studies show that in cultures and countries where boys and girls are both encouraged to tend house, they have greater work/life policies for men and women alike," she says.

When you observe little boys and girls playing in a park their behavioural differences often match the stereotypes perfectly. The question isn't whether these boys and girls are behaving differently, but whether or not we — consciously or not — made them that way.

In light of recent understandings about neuroplasticity, where brains literally change according to the environment, you do have to wonder what role we all play – even as far as the butcher, the baker and the reveal party planner – in forcing children to assume rigid behaviour roles.

Kasey Edwards is the best-selling author of four books: 30-Something and Over It, 30-Something and The Clock is Ticking, OMG! That's Not My Husband, and OMG! That's Not My Child. www.kaseyedwards.com