A RIDDLE I heard on the radio while driving to the supermarket caused me much consternation this week.

I was never much good at riddles. My brain just doesn’t work that way.

No, I’m being too kind to myself. I’m just not very bright.

Anyway, this riddle, which you may have heard before (I hadn’t) goes something like this.

A man and his son are in a car when it is involved in a bad accident. They are both rushed to hospital. Tragically, the man dies of his injuries.

His son is rushed into the operating theatre for emergency surgery.

The surgeon takes one look at the boy and says: “I can’t operate on this boy. He’s my son.”

How can this be? His father’s dead, I thought.

Of course, the radio programme didn’t give the answer straight away.

I sat outside Asda for about twenty minutes waiting. I didn’t move until they read the answer. Had the surgeon come back from the dead, I thought? Did the boy have two fathers?

I thought of so many variables, except the most obvious one. The surgeon was the boy’s mother.

I’m still furious with myself. In this very column I have prattled on about unconscious sexism, the impact of Barbie dolls and the under-the-radar seeping bias of a patriarchal society for about two years now.

I’ve railed against the Disney princesses, the suggestion that women can ever be responsible for rape, and the brutal misogyny of violence against women.

Yet I had committed the very sin I fume against society for.

I went to a girls’ school. We never faced the classroom sexism. We were encouraged to go to university, study science, maths or languages, become engineers or academics. It never even occurred to us that the glass ceiling existed.

So it was a shock to discover I too, am unconsciously sexist. Some of the undercurrent of our chauvinistic society has seeped in to my brain.

After the anger directed at myself, I was comforted that I’m trying my best to stem any similar thoughts in my own daughter, who is reading a fabulous book recommended to me by my fellow columnist Joanna Morris.

Good Night Stories for Rebel Girls has been a revelation in our house, with even my football-loving (and very occasionally subconsciously misogynistic) eight-year-old son taking an interest.

Sweeping aside the traditional history books in which really only men's achievements are celebrated, this book delves into the stories of heroic women from Elizabeth I to Amelia Earhart, kicking Disney and his princesses into touch and providing real, often gritty, role models for young girls. None of these bad girls needed rescuing by men.

Holly’s nose has barely left the book since I gifted it to her last Friday.

There’s even a blank page at the back, for the reader to write about themselves and how they are going to change the world. Inspired by Venus Williams, Malala and Aung San Suu Kyi, she’s written her own entry.

Watch this space.