Dom Joly: Daddy's little jumper – it seems to run in the family

My daughter stood, frozen, on top of the cliff. It was about a 20-foot drop down into the dark waters of Lake Joe and this would be the biggest jump of her life so far. From our speedboat below, her mother was screaming: "Don't let him force you to do it. You don't have to do anything you don't want to ..." Parker turned towards me. "Do you think I should do it, Dad?"

This was a loaded question. I certainly knew that she could do it, but whether she should was another question entirely. Just seven feet behind us, on the flat rock, lay a pair of trousers, a T-shirt and some expensive sunglasses – clearly put there by someone before a jump – but there was nobody else on this island and no sign of another boat.

I know there have been "tombstoning" accidents recently – after much longer jumps – but cliff jumping has long been a bit of a tradition on my side of the family. As a kid, I remember clambering up rocks overlooking ice-cold river pools in the mountains of Lebanon. My dad would swim around my "drop-zone" and check for hidden rocks. When he'd finished his survey, he'd point to the perfect spot, and I'd launch myself into the still, Levantine air and plummet.

There would be an underwater moment of total stillness, as the brain caught up and went through a quick checklist for signs of life. Then, the legs would kick in and push me back up to the surface. My dad would say something very restrained like "good jump", and I would secretly well up with pride. It was a thing we had between us – a shared adventure that allowed him a way of breaking through his usual emotional reserve.

And now it's my turn. The lakes where we spend our annual summer holidays in the Muskoka region of Ontario are lined with towering granite cliffs that hang over enticing watery landing areas. The first year I came here, I was taken to a bay whose "jumping cliffs" had been used for generations.

This being Canada, someone had marked the heights of the various jumps in chalk on the cliff face – there was even an old rope attached to a tree to help you get out of the water. My first jump was the biggest – 55 feet down into the luscious, thick, black waters in front of my new Canadian in-laws who were bobbing up and down in the speedboat. It was an exhilarating jump and the pressure was such that it ripped my expensive watch off my arm and sent it down into the murky depths, never to be found.

In the years since, we've tried to find our own jump sites. Whenever we spot a potential, I edge the boat right up to the base and use my depth finder to ascertain whether it's a goer. If it looks promising, I dive in, as my dad did, and check for rocks.

Last year we came across this deserted island with almost perfect cliffs. It's way up in the less populated north of Lake Joe and we have claimed it as ours. So here we were, my seven-year-old daughter and I, on top of said cliffs on our conquered Canadian island.

I tried a countdown: "Three ... two ..." She screamed at me to be quiet and we both stood in silence, as I wondered whether the owner of the discarded clothes might be a shy nudist who was now hiding in the nearby bushes waiting for us to disappear. Suddenly, she was gone. Parker had launched herself into the air and I saw her dropping down ... she hit the water cleanly and disappeared. I held my breath for a second until she surfaced, a huge grin over her little face – looks as if it runs in the family.