Parents throw an awful lot of mud against the wall to find out what their children are good at, even though they think they are good at everything already.
There is never any reason not to throw more mud.
We threw a huge amount of mud at our children's walls, and that came back to me over the past few weeks when our daughter Shannon visited from Chicago with two children of her own.
The cycle is about to begin all over again. We ran Shannon through everything.
I'm flicking through the cheque butts from the family archives as we speak ... piano, Scottish country dancing, speech, table tennis, violin, horseback riding, ventriloquism, swimming, Sudoku ... she smiled beatifically through them all.
Finally she found herself on the Playhouse Children's Theatre stage in Albany St.
My wife had rung Repertory matriarch Ruby Hannan, who thundered back down the phone that she was full.
But you know, Dunedin, a word that I knew Ruby's son, and Shannon was allowed to audition for the chorus.
The play was The Red Dragon, and the lead girl went down after a couple of days.
Shannon was called from the far corner of the stage to take over the role.
Suddenly our quiet always-dreaming daughter who never said boo, was striding around the stage entertaining hundreds of people daily.
We had finally found the right mud.
Ten years later she was in Chicago, after being offered a drama scholarship by Roosevelt University.
In her second year, she acted with a man who had lines with Robert De Niro in Midnight Run. In a train.
We got the video out and watched the scene repeatedly, knowing our daughter was now only two degrees of separation from Hollywood.
Two years on, she was there, nannying for her Chicago friend, Liesel Matthews, who had the lead in The Little Princess.
But while every other aspiring actress in the world would have carried CVs and performance videos into that inner sanctum, Shannon never gave it a thought, she just looked after Liesel.
We had to cut information from her with a scalpel.
She admitted to lunching with important people, but it was so hard remembering names.
One day she stood next to Robin Williams for a while.
He was nice.
Then came an offer to nanny Mel Gibson's seven children, which, in Hollywoodspeak, is called a lucky break.
Take it, we shrieked, tell him you're an actress.
But Shannon went back to college, then marriage, then motherhood.
That particular piece of mud had fallen off the wall. But it had changed her life.
Liesel chose a spectacularly different path.
After starring with Harrison Ford in Air Force One, she made the cover of The Wall Street Journal by suing her father for six billion dollars.
Liesel, heiress to the Hyatt empire and a bit more besides, settled out of court and went straight into the Forbes Rich 400 List.
Only in America.
So here we were last week back at the Playhouse Theatre, 30 years on from The Red Dragon, Shannon sitting with Jude, not yet a year, and Rowan, (4), all three of them eyes wide as the rich old curtains - purloined from Government House - rolled back to reveal the colourfully-costumed non-digital wonder of children's theatre.
My wife has helped write and direct plays there for some time.
Her mother (81), leans over and says she must be one of the most well-known people in Dunedin by now with all these plays touching so many children.
I think of Peter Chin, Brendan McCullum. Speedy. You're probably right, I reply. She smiles proudly.
Four generations transfixed in four different ways.
The old and the good can do this, and preserving the old and the good, something you can come back to after 30 years and nothing has changed, is what Dunedin does best.
This is a very special kind of mud.
• Roy Colbert is a Dunedin writer.
