I am so looking forward to my trip with my son next week. First up is Cern, in Switzerland, where my son gets an hour on the Large Hadron Collider all to himself. On Tuesday, it’s off to the National Portrait Gallery in London, where an exhibition of his crayon selfies is on show (royal attendance is rumoured). Wednesday he’s being filmed for the BBC completing a Rubik’s Cube with one hand.

Thursday, he’s on at the National Theatre, where he’ll recite the works of Shakespeare from memory. Friday, we’re off to Vegas to win a fortune at blackjack. I’ve bought the matching suits and sunglasses and, get this, he gets to fly the plane home himself.

It is a whirlwind being the father of an autistic child – especially one as multitalented as mine. Some autistic children only have one special talent.

OK, so this isn’t true. I am the father of an autistic child, and the first question I’m always asked when the subject of my son comes up is: “Does he have a special talent?” because everyone has read The Curious Incident of the Dog in the Night-Time and seen Rain Man, and assume all autistic children have special powers.

My son doesn’t. He’s 16, is non-verbal and his life skills are rudimentary. He’s on one part of the autistic spectrum. Rain Man sits somewhere else on a bit made from celluloid.

I don’t expect the whole population to trawl through reams of data, case studies and science papers on autism, but at least get to understand the basics. Let’s start with a simple question. Are all neurotypical people – those without a diagnosis of autism – the same? If your answer is yes, proceed directly to the nearest Borg recruiting office. If your answer is no, pat yourself on the back (although it doesn’t make you a genius).

This is what it does to me – I can’t help it. I get facetious. When, for instance, we were calmly queueing to pay for some apples in Waitrose and my son decided to use them for baseball practice, pitching them wildly into the neighbouring McDonald’s, did anyone smile and think, “Oh, bless him, he’s autistic”? Or when we were wrestling on the floor as I tried to get him to stop attacking me, or when everyone’s food in a restaurant is fair game – and I don’t just mean on our table – there is no applause, no One Show researchers begging me to bring him on for a demonstration or recreation of his baseball glories. And I’m not sure his naked trampolining is going to earn him an Olympic medal anytime soon.

Given that it’s simply bad form to tell a well-meaning stranger where to go, I have often resorted to being facetious. When my son was six, I took him to watch one of his older cousins paying football and two girls approached and began talking to him. Of course, they got properly cold-shouldered and inquired of me: “Why does he never say anything?”

To which I replied: “He does, but only to very pretty girls.”

But it’s not the way I’ve always dealt with it. As part of a dedicated team raising my son, explaining him to strangers has been exhausting.

So, most often over the last 16 years, I’ve been a model of polite solicitude. Like a walking GP surgery pamphlet, I’ve divided my responses into easily digested chunks, subheadings: “What is the Autistic Spectrum?” and “About Diagnosis”. At other times, I’ve countered pub banter with “No! Just because your boss is a rude, arrogant shit who won’t look you in the eye, doesn’t mean he’s autistic.” It sometimes feels like an endless battle.

This gets me so irritated because good information is out there in plain sight. On Twitter, on Facebook are millions of genuine first-hand experiences and real, of-the-moment findings. It is thus a 21st-century species of ignorance, one that masquerades as inquisitiveness, to glean “knowledge” from media that is intended to entertain to form one’s view of autism. It is from the “well-drawn” character who fills us with wonder – whether it be standing next to Tom Cruise as he counts cards, or making us laugh with their complete lack of social understanding that “misunderstandings” can arise.

Plot devices and stereotypes are not real. You cannot reduce autism to genre conventions, because every person with an autism diagnosis is different. My son is me with a particularly tough veneer of autism: he’s a bit lazy, finds most things hilarious and is given to bouts of self-injurious behaviour. But he’s not less than me – in any way. He’s not less.

And if you took the trouble to know him, you’d realise that in most ways he is more. That’s the kind of knowledge that everyone needs to have.

It hurts me to have to write this. I don’t like having to speak on his behalf, but he isn’t able to and I hate having to rely on supposition. It would be easier for me to state that he couldn’t care less. But I can’t say that because he can’t tell me. It hurts less when I can provide him with a blithe, devil-may-care attitude to other people’s opinions of him.

Am I overreacting and being chippy? My son’s also Jewish. Would it be OK if a stranger asked in polite conversation whether he was fond of money? Or asked an equally ignorant question of a Muslim father with regard to one of his children? Of course it would not.

The question, “Does he have a special talent?” is not sinister in itself, but the ignorance behind it is, because it speaks of a world where just being human and getting by is insufficient to get noticed – a world where even the most vulnerable in our society have to aspire to Britain’s Got Talent to be seen of value.

Shtum by Jem Lester is published by Orion Paperbacks (£8.99). To buy a copy for £7.64, go to guardianbookshop.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min. p&p of £1.99.