In the latest update to his blog, Jack relates how he and his sisters have swapped roles with his engineer parents in the run up to Christmas.
For years Dad has pretended that I actually like Scalextric. And every Christmas he buys me a new set or track extension. He waits until I've unwrapped it and said "thanks Dad, you have nooo idea how much I wanted this", and then he snatches the box, sprints upstairs and adds it to the humongous racing network in the attic.
Two hours later, he's back down for the turkey. But you can see he's not really with us: in his mind he's still up there, racing Lewis Hamilton in his McLaren Mercedes (I'm fairly sure that's what I'll be getting this Christmas).
I've stopped going up there. Sitting hunched up watching little cars fly round a track? Wearing your knees out collecting them from the corners of the room when they fly off the bends? Hunkering down with a little soldering iron fixing the broken contacts? No thanks. Well, if Dad ever gave me a look-in, then maybe, but the man who holds the soldering iron rules the world. All he ever let me do was glue the broken wing mirrors back on. And you never give strong glue to a seven-year-old. I had to get my head shaved in the end and my own hair glued to my hand for days.
In a rare moment of subversion, Mum bought Mario Kart for the Wii this summer when it looked like the rain was going to be permanent. Now that's what I'm talking about! Bits flying everywhere, but no one has to pick up anything when you scream off a corner and slam into the foot of the ravine. And you've got the chance to transform into a jet rocket thingy and scorch all your opponents. I reckon Scalextric could learn something there.
Dad was predictably tetchy about the whole "sitting on the sofa and cheering at a television screen" thing.
"(A)," he says (you can tell he's angry when he starts bullet-pointing his thoughts), "it won't teach you anything. Scalextric teaches you about the forces operating on bends, for a start, and gets you thinking about whether you shouldn't bank those turns a little higher. There's a generation of children growing up who think cars just plop down in the middle of the road once they've crashed - it's not worth paying for more than one driving lesson for any of you because you'll all be dead by the time you've turned the first corner.
"(B), you don't learn anything sitting on your bums with a stupid steering wheel in your hands." ("But that's the same as (A)," protests Amy. Dad carries on, relentless.)
"What I mean is that with Scalextric you've got to work out how much space you need to play it, and then you've got to build it, and then you've got to get the cars tuned up..."
"Yeah, Dad," I say, "and then you've got to stick a screwdriver down the narrow bits of the track to make them work better, and you've got to rebuild the handsets every couple of weeks and fiddle about with the..."
"But it's all good," interrupts Dad. "It's all about solving problems."
"But where's the fun in that?" I ask. "What if I just want to race?"
We stare at each other in mutual incomprehension.
"You know, I bet Lewis Hamilton never had this sort of conversation with his dad," says Mum, to herself more than anyone else.
Dad produces his trump card. "Computer games are no good, not compared to Scalextric, because they're not real."
We all go off in howls of laughter.
"Listen to the Doctor of Philosophy!" hoot the twins. "Watch it, I am a doctor of philosophy," says Mum. (It's true. She did do a doctorate and she's a Dr, not a Mrs. She loves putting them right at the airline check-in desk when they try to hand the tickets to Dad. On the other hand, if anyone had a heart attack on the plane, it wouldn't be much comfort to hear about complex system structuring in global IT networks. Although it would give them something really absorbing to think about in their last moments.)
"Who would have thought that 'I think, therefore I am' was actually a cry from the questioning intellect at the heart of the slot car community?" asks Alice.
"Or as the joiner has it, I countersink, therefore I am," says Amy.
"Or as the unwashed teenage boy has it, I stink, therefore I am," says Alice, with a nasty look at me.
"I hyperlink, therefore I am?" says Mum, not to be outdone.
"I hate you all," says Dad. "But I'm still right. The crashes and the fixing, it's all part of life. It's real. It actually happens. There's a cost to driving too fast or making a mistake on the bend. Even if the cost is crawling to the far corners of the attic every two minutes or burning your finger on hot solder. The trouble with you is you think there's no cost to a game."
We're impressed. Then he spoils it by going totally off-piste. "And that's why we watch Formula One, isn't it? Because we're all secretly hoping they'll crash."
We all look at Dad, appalled. "That is so not the right thing to say," snaps Amy.
Dad appeals to Mum. "How have we raised kids who think nothing of smacking each other in the face on Wii Boxing but can't contemplate the very real possibility that people might die in motor racing?"
"The shadow of Ayrton Senna indeed grows fainter by the day," says Mum, who has suddenly turned into Yoda.
"Who?" I say.
"But then humankind cannot bear too much reality," adds Mum. "TS Eliot."
"I don't suppose he was an engineer, then," says Dad.
"No, and I bet he didn't get rubbish Christmas presents every year," I say, but under my breath. I'm hoping I get Lewis Hamilton this year too. Dad deserves it.