My 17-year-old is watering the neighbour's plants (for a fee). One evening, unable to find his trainers, he squashed his feet into my husband's shoes and disappeared off next door.
Just 15 minutes before this, I had tried to impose some sort of order on the random footwear littering the hall. So when my husband shouts, 'Where are my shoes?', I shout back, 'In the shoe rack!'
Thuds from the hall. Husband stomps around, getting increasingly irritated. The shoes, apparently, have disappeared into thin air.
But then, having been trained by my teenagers to weave random scraps of information into a badly sewn patchwork, I guess what's happened.
Husband is irate. 'Why doesn't he wear his own shoes?' he says. 'Why's he wearing mine?'
I stare at him astonished. He's so cross. And then I think, maybe this is not really about shoes. Maybe he's feeling sidelined, displaced by the new generation. Because teenagers do that to you sometimes. They take up all the space. They eat all the food. They fill the house with the noise of their choice. You end up feeling like an arthritic dog looking wearily at a two-year-old springer. You end up wondering how, and why, you lost control of the remote.
The next morning, late for work, I'm in a panic.
'Has anyone seen my hairbrush?' I shout.
No one answers, of course. They're all asleep.
I find the hairbrush underneath a pile of my daughter's clothes in her bedroom.
Forget the displacement theory. What's extraordinarily irritating about living with teenagers is that they keep borrowing all your stuff.
And they never, ever put it back.