Lorenzo Lotto's 'The Physician Giovanni Agostino della Torre and his son, Niccolò'

To me though, the son looks completely uninterested in his father’s work and unimpressed by his importance. Which reminds me of the time my own younger son said to me, when he was around 18: 'you’re unnecessary.' I’d spent my whole life trying to convince him of how great I was, but to him, I was just an idiot, someone who paid the bills. 

This was a slight sting to the ego, but as I reflected later on his comment, I realised that to be unnecessary is in fact liberating and strangely pleasurable. For one thing, I hope it means we’ve done a reasonable job of bringing up this child. The aim of parenting should be to produce a cheerful, self-sufficient adult, one who can tie his own bootlaces, wash his own clothes, cook his own meals, do his homework without being nagged and yes, find his parents to be unnecessary. 

Now, young Niccolò looks vain to me, even unserious, more interested in his beard and headgear than his illustrious and distinguished Dad. And he looks almost reluctant to be in the family portrait. He’s got better things to do. He probably wants to go and hang out with his mates. It reminds me of a million family photos with earnest parents and their half smiling kids, desperate to get away.

Possibly the Dad is disappointed by his vain offspring. On studying the notes to the picture, it appears that young Niccolò did not follow in his father's footsteps and heal the sick. Instead he was more worldly and money-orientated and became one of his town’s wealthiest citizens.

This very much reminds me of my older son. He watched me making a precarious living writing books and editing magazines and seems to have though at some point: I’m not going to do that. He's now a Product Manager at a Fintech (whatever that is), is earning more than me, and has already invested in his first flat. 

I’ll admit that when I realised he wasn't going to be the new reincarnation of Oscar Wilde, I was slightly disappointed. But like being called unnecessary, his choice reduced any self-importance that might have been bubbling up in me (and which I detect in Giovanni). That’s good. Self-importance is very dangerous. 

As the great 20th-century philosopher Bertrand Russell said: 'One of the symptoms of an impending nervous breakdown is the belief that one’s work is terribly important.' Dads, then, should be grateful to their sons for puncturing any nascent pomposity.