I used to think it was just the floor and the walls that were regularly pasted with food and drink, till I glanced up from reading a book on the sofa and saw strawberry milk all over the living room ceiling.

It had formed a spectacular spray effect, as if Jackson Pollock had popped in and decided our ceiling was a suitable canvas for his next splattery masterpiece.

My wife was sitting at the dining table with an innocent look on her face, also reading a book. She was directly below the new artwork. There was an empty glass on the table in front of her. I went and fetched the mop from the kitchen.

She looked up as I came back in.

“What are you doing with the mop? This room is carpeted,” she said.

“I know,” I said. “Look up.”

She did, and promptly burst out laughing. So did I.

“Um, that wasn’t me, was it?” she said, still laughing.

“Yes, Michelangelo. It was. Only that isn’t the ceiling of the Sistine Chapel. And we’re running out of milkshake.”

She glanced down at her hand on the base of the glass.

“It’s the HD,” she said.

“I’d guessed that,” I said, and began mopping the ceiling.

HD is Huntington’s Disease. We’d discovered a few years back that my wife had inherited it from her dad. The symptoms only begin to emerge in adulthood. One of them is uncontrollable and dramatic limb movements, often taking place without you realising you are doing it. People with HD also need a high calorie diet to avoid wasting away. Hence the constantly topped-up milkshakes.

We were still laughing when our older son and his wife popped in.

“The photographer from the magazine is here and wants us out in the garden for the picture,” said my son.

“The journalist is out there, too. She’s finished her interview with us about Mum’s book, but says she has one last question for you. What’s your greatest weapon against an incurable family illness? Thought you’d want a heads up to think about it before you get out there.”

My wife and I both looked up at the ceiling and then at each other.

“Laughter,” we said at the same time.

“Get your younger brother and tell them we’re coming,” said my wife. “I just need to get this pink stuff out of my hair first.”