My son is a sexist. As much as a four-year-old can be sexist, at least.

He’s started conforming to very old fashioned stereotypes: pink is girlie, Mummy’s not allowed to play with male action figures, girls don’t do the driving (or hold toy guns – for fear of breaking a nail, presumably) and, of course, boys always save the day.

It’s surprised us. We’re not bohemian enough for full-on gender neutral parenting, but we’ve been active in reinforcing equality and positive gender roles since he was born.

Pink is for everyone, Mummy can play with whatever toys she likes, and girls do their equal share of driving and saving the day. Thanks very much.

So where has this come from?

Is it that kids are just naturally inclined towards certain gendered identities? Is it something we’ve been doing unconsciously as parents? Is the media to blame? Or perhaps the inevitable influence of other children?

People say it’s biological; that male and female brains are hardwired towards different interests and behaviours. Indeed, from a very early age – way before he had any concept of gender – my son certainly loved ‘boy’s stuff’: trains, diggers, dinosaurs, smashing things up.

And you might think all this is innocent enough. But I can’t help thinking – isn’t this how the damaging stereotypes that have long defined men and women begin?