WE'RE AT Océanopolis, a vast aquarium in Brest, Brittany, which is housed in several dramatic white domes. "In the olden days," says one of our sons, "when you were young, I bet you thought all buildings would look like this." To humour him, I agree. "And I thought we'd eat little pills instead of proper roast dinners, which would dissolve on our tongues and activate our taste buds," I add.

My son snorts. "What's so sad," he continues, "is what you thought was really cool and modern back then."

"Like what?" I ask, paying the admission fee and steering my family into the tropical zone.

"Like Wimpy!" he exclaims. "You thought it was cool to go to Wimpy for a rotten old burger."

"Not really," I say. "But it was new and it seemed really ..."

"And you believed that machines had brains and thought like human beings, ha ha!" he adds.

"No I didn't," I protest. "I've never thought that "

"Yes you did. You still do. You said that with Sat Nav, if you go a different route to the one it says, it thinks you've gone the wrong way " His laughter ricochets around the aquarium's observation area. He takes a few cursory pictures on his whizzy new digital camera. "Your computers were massive," he raves on. "They needed special rooms with ventilation in case they overheated, and they only had dial-up connection. Crazy!"

"And people died of toothache," his sister snorts.

We move into the polar zone, where our son takes some hasty snaps of the penguins. "It's not like our day," he crows, waggling his camera, "when we can zoom in and crop and delete our pictures. I've got over 100 shots on here. I've taken pictures of everything." He makes J and I watch as he flicks through them at eye-boggling speed. "And your first mobile phones," he sniggers, "were massive. I've seen 'em in the Museum of Scotland. And you were so excited when calculators came out, and you thought they had little men inside them, doing the calculations "

"It wasn't all bad," J protests as we enter the temperate zone, where delicate seahorses are twirling around fronds. "What about all those old programmes we showed you on YouTube?"

"Like Dr Who," our son cackles, "where the Doctor was so old, like about 90, and he fell in love with this really young woman "

"And this unstoppable war monster thing," honks his brother, "was just an old box with a gun strapped to it "

"Dr Who was scary back then," I insist. "It was the scariest thing on TV."

"What was that show with the weird wombat thing playing a flute?"

"Tinger and Tucker," mutters J, studying tiny wriggling creatures in the langoustine nursery. Although our son is still taking numerous photos, he doesn't seem to be looking at anything with his real eyes. To me, it seems like going to a gig and spending the whole night capturing it on your mobile. I'm beginning to feel even older than Dr Who in his baggy suit.

"And The Clangers," he continues, "who don't even talk. You know what they were?"

"Little alien beings," I murmur.

"Perverts."

"How can you possibly say that? What evidence do you have that makes you ..."

"They spent all their time perving at the iron chicken through a telescope." He grins triumphantly, then turns to photograph a passing turtle. I watch him, marvelling at the speed at which he clicks through his camera's myriad of functions. "No!" he screams suddenly, stabbing at the off button.

"What's happened?" I cry.

"I've just deleted all my pictures!" All the shots he's taken of the French markets, the beaches, our boat trip to Belle Ile - all gone. We try to console him. He is devastated. "Want to go around Océanopolis again," I suggest, "so you can take pictures of everything?"

He nods tearfully and grips my hand.