Boys love to rough-house, for a number of reasons.
One, they're a lot like dogs, because they're bursting with physical energy – give them a good run every day or you'll have problems.
Two, as long as they get to win, or at least honourably draw, it makes them feel confident and strong – how many times have you heard a scrawny little lad boasting about his big muscles?
And three, they get to beat up a large adult, who generally happens to be their father.
Now, this was all well and good when my lad, Ben, was a nipper. We'd playfight, and I'd pretend to be knocked to the ground, or felled by a mighty punch.
Then he grew. And grew. And grew. Until, on the cusp of teenage-hood, he's massive, very strong and packing a lethal right cross. Getting whacked by my son is no joke now, believe you me.
This presents a number of problems. Chief among these is the 'free punch'.
Picture the scene: 'Plee-ease,' wheedles Ben, 'just one!'
'No thanks,' I reply, remembering the last time I agreed, then bitterly regretted it.
'Come on, just one. One! I promise I'll hit the shoulder. Please!' he pesters, bouncing round the kitchen pulling silly faces until I crack up and give in.
'Right, just ONE,' I say mock-fiercely, 'and aim carefully.'
'Yesss!' says Ben triumphantly, drawing back his fist and driving it into my shoulder.
'Owww – you hit the bone again!' I say, grimacing.
'Argggh, run away!' cackles Ben, rushing off to escape retribution.
Another problem is that he attacks me, without warning, at the worst-possible moments. Remember Cato in the Pink Panther films, who was always leaping on Clouseau when he was in bed with a girl, or something, because he'd been instructed to attack at any moment? Like that.
Except it's rarely that glamorous – I'm usually carrying a heavy pot, or glass of juice, or something, and it all goes horribly, messily wrong.
Worst of all though (and I haven't admitted this to anyone yet) is that some day soon, he'll be stronger than me. I feel it coming, his body growing ever more powerful as mine succumbs to a succession of minor injuries.
One day, we'll be wrestling, and he'll beat me. No pretend falls, no 'Wow you're so strong!' Just a humiliating defeat: our very own Oedipal moment.
And I know this is what happens, with fathers and sons, that everyone reaches this tipping point. But I must confess I'm not looking forward to it one bit.
Better get a few victories in while I can...