Finally we go out and buy a Christmas tree. I am not concentrating. We come home with one so big it makes the living room feel like a rabbit hutch.
"It's the best one we've ever had!" says my daughter with delight.
I wonder where Grandma is going to sit now that half the sofa is taken up with branches of sharp pine needles.
We open up the bag of decorations. Son no. 1, home from university, picks over the battered angels and one-legged Santas.
"How come," he says, "all the stuff I made years ago has disappeared?"
Your job, as the mother of teenagers, is to know the exact whereabouts of everyone's treasured possessions – everything from iPhones to childhood memorabilia.
"Nothing's been thrown away," I say quickly. You only have to look at the rubbish spread out on the floor to realise this. My only comfort is that this year the home-made star made of cardboard and tin foil will be so near the ceiling that no one will notice its advanced state of dilapidation.
"And what about Squashed Bird?" says son no. 2. "Where's Squashed Bird?"
Squashed Bird has hung from the banisters every Christmas, like flattened road kill. "It's in the bag somewhere," I say.
But now I'm not so sure. Did I turn ruthless last year and throw away crumbling snowmen and flaking angels? Ten-year-old salt dough covered in poster paint and glitter? I feel horribly guilty.
Son no. 1 looks accusingly at his sister. "It seems to me," he says, "that the only decorations left in here are the ones you made."
She looks at him with withering scorn. "It's not my fault," she says, "if yours fell apart."
"We could always buy some new decorations," says my husband, coming into the room just in the nick of time. "Chocolate decorations. Then we can eat them."
The moment of tension vanishes.
Chocolate. Never forget. It's what gets you through Christmas.