I told her she shouldn’t have been snooping, but that issue was soon buried by the enormity of what she’d found. Crumpled in his pocket, there was an admission ticket to the rugby league. Then, in his cupboard, a banner for something called the ‘West Tigers’.

‘Maybe it’s some sort of ecological trust, to save the Bengali tiger,’ whimpered Jocasta hopefully.

‘No, darling,’ I said. ‘We must face facts. Our son has become a rugby league supporter.’

‘But where will it end?’ said Jocasta, letting loose a low sob. ‘I always imagined him settled down, with a DVD collection of great films and some wonderful books.’ A tear trickled down her face. ‘Not slumped in front of The Footy Show,’ she said, keening.

I tried to reassure her. ‘Look, a couple of experimental games of league doesn’t always lead to The Footy Show. Let me talk to the lad.’

Do children always do the opposite of their parents? If the father works for Flick Pest Control, does the son become an entomologist? If the mother is a world-famous violinist, is the daughter naturally tone deaf? And if the parents know nothing about sport—if, like Jocasta and me, they have zero interest in sport—is it inevitable the children will follow rugby league, the most sport sport of all sport?

‘We understand you need to rebel,’ I say to Batboy later that night, ‘but why not develop an interest in a sport such as ice-skating, or synchronised swimming, or even AFL? At least they’re artistic.’ Unbelievably, Batboy just rolls his eyes and walks off. Sometimes you just can’t talk to teenagers.

In the typical movie storyline, the artistic boy is always trying to escape his sporty parents. It’s never the other way around. In Billy Elliot, for example, the child is a ballet genius, confronting a parochial and violent father. You’ll remember the harrowing scenes in which the brutish father forces Billy to learn boxing—the artistic boy clobbered as the stubborn father looks on.

If it were our family, the whole story would be in reverse. In fact, I’m thinking of making just such a film under the title Batboy Elliot.

Scene one opens with Batboy Elliot coming up the front steps of an inner-city house. Inside the kitchen his father is practising ballet steps with other members of his local men’s group. Tofu burgers, brought by one of the men, sit ready on the benchtop. A large pot of camomile tea sits brewing nearby. The camera cuts away to Batboy Elliot nervously hiding his new boxing gloves in his bag as he comes up the hallway.

‘Hi Dad, hi chaps,’ he says as he walks through the kitchen, willing his voice to sound cheerful. No way does he want to get involved in another argument. Boxing and footy are Batboy Elliot’s dreams. Why can’t this narrow and stultifying society of inner-west trendies understand that?

Suddenly, the weedy voice of his father shoots out. ‘Batboy Elliot, what’s tha’ on thy chin?’ (Even though the father is an inner-Sydney trendy, he talks like a Lancashire coalminer for reasons that remain unclear.)

‘Nothin’ Da,’ says Batboy, speaking, inexplicably enough, in the same north-country dialect. ‘There’s nowt amiss, like, Da.’

‘Come ’ere, and let thy da look,’ says the father, his voice thick with concern. Reluctantly, Batboy walks towards his father, who gently angles the boy’s chin to the light.

‘Thee ’ave a huge bruise on thy face. Ay! Thee bin boxing again!’

The two stare at each other. ‘Say summat, lad,’ the father gently insists, his north-country accent getting thicker the longer the scene goes on. Batboy Elliot is in agony. His father is using his ‘caring and sharing’ voice. Why can’t he just scream and belt you, like the fathers in the movies?

‘No, Da,’ says Batboy finally, the camera hovering on the bruise. ‘It was a ballet injury. I was trying for t’ high leap, just like Baryshnikov, un hit an overhead awning.’

‘I don’t believe thee, lad,’ the father says, a tear running down his face.