Peppa Pig is history. Our three-year-old daughter's new obsession is the CBeebies programme Topsy and Tim, a remake of the popular children's books from the 1960s about a twin sister and brother.
Her favourite episode is called Marble Run, in which Topsy and her female friend, annoyed at Tim and his playmate Tony hogging all the marbles and plastic chutes, outsmart them by making their own contraption out of toilet-roll holders.
Last week, then, when I spotted a marble run toy on Marks and Spencer's website, I decided to buy it for our daughter for Christmas. But, just as I was about to click "Add to basket", I noticed its full title was "Boy Stuff Marble Run Toy". Since when were marbles only for boys?
The packaging was in neutral colours, but on the corner of the box was a skull and crossbones with the slogan "Boy Stuff". Worse, there was a whole range of "Boy Stuff", including a "Dinosaur Activity File" (which, presumably, features a list of M&S executives) and a "Boy Stuff 500 Jokes Book". Is this because M&S thinks little girls can't tell jokes?
There was a parallel range for girls, called "Little Miss Arty", based on fairies, princesses and handbags.
If our child were a little bit older, she would be able to read the word "boy" on her marble run box and think this toy is not for her. Your domain is only princesses now, she would be told – in spite of her loving dinosaurs and marbles.
It is quite extraordinary that M&S, probably the most prominent retailer in the UK, thinks it is perfectly normal for toys to be segregated along gender lines.
Enraged, I tweeted a link to the "Boy Stuff" range and it was taken up by the campaigners Let Toys Be Toys and Everyday Sexism.
By the next morning, after being inundated with complaints on Twitter, M&S responded by pledging that all their toys will be "gender neutral" by spring 2014 – a decision apparently made earlier this year, but not made public until now.
In fact, when I checked, the retailer had taken swifter action and already ended its gender segregation: on its website, the label "Boy Stuff" had been replaced by "Kids' Stuff".
This is a victory, but everywhere you look, retailers continue to think that girls want handbags and boys want trains. John Lewis has a girls' range online, featuring jewellery kits; its boys' range is all Batman and Star Wars.
Campaigners like Let Toys Be Toys and Pink Stinks say that in the 1970s (when I was growing up), shops did not offer such gender-stereotyped toys. There were Sindy dolls in my toy box, but also Lego and marbles.
The announcement by M&S has triggered a backlash; it's accused of being "cowards" for "caving in to the PC brigade". But try telling a little girl that some toys are out of bounds for her.
By the age of five, or six, children are very aware of labels: stick the words "Boy Stuff" on a box and a girl won't play with it.
And this matters in later life: giving a girl a chemistry set at seven will give her more confidence to study science at school.
For now, our daughter is blissfully unaware of how the world expects her to be: she refuses to wear a dress and a doll dressed in pink sits at the end of her bed, ignored.
I ordered the M&S "Boy Stuff Marble Run Toy", anyway, as a small act of defiance.
I predict she will play with it for hours on end – once I get rid of the packaging.