My brother is severely autistic, I say. They assume he is a savant, a prodigy, a genius

The conversation I wish I didn't have to have, by Rhiannon Lucy Cosslett

"Do you have any brothers or sisters?" the newly introduced stranger asks. It is an entirely predictable, well-meaning question that I do not dread, exactly, but one that requires the summoning of a certain amount of energy, usually held in reserve.

"I have two brothers," I say. "The eldest is 22." I know from experience what the next question will be. It will involve jobs, or universities, so I preclude it almost instinctively. "He's severely autistic," I say.

Some people hear the "severe" and understand immediately; most do not. They have come across articles and seen films and read The Curious Incident Of The Dog In The Night-Time. They have witnessed the postmortem diagnoses of historical geniuses. The cultural fascination with a certain type of autism has rubbed off on them. I do not blame them for this, but I hate the next question all the same: "Is he very good at maths?"

They assume he is a savant, that he recite train timetables from memory, or has a special talent for intricate map-drawing, is a musical prodigy, a scientific powerhouse, a genius. They assume that his non-neurotypical brain will go on to achieve great things, driving human progress forward. This is the autism of the popular imagination, inspired by films and works of literature, all brilliant. It is categorically not my brother, who is nonverbal and unlikely to be recruited by GCHQ any time soon, or indeed ever.

"No," I say.

They ask if he will ever live alone (no, I say), or have a girlfriend (no), get married (no), have a career (no, never). They look sad about this, and sometimes ask if I am sad. It is sad ,I say, of course it's sad, but to feel regret about him missing out on all these things is to feel regret about who he is. It would be strange to wish that my brother had never had autism, because then I would be wishing he were someone else.

When I was at school, we had to do a speech in English class. I did mine about my brother, not only because he has so wholly and completely defined my life, but so that I only had to have "the conversation" once. There was a Q&A session afterwards that lasted almost as long as the speech itself. My classmates asked curious, kind questions in the only way that children can: "What type of music does he like?", "What's his favorite place?". "What sort of person is he?"

I like these questions. When I talk about my brother now, I want to tell the stranger this: that my brother smiles, and laughs, often. That he loves rock music, and penguins, and going to Costa for a coffee. That as a child he was small and blond and beautiful; that he would creep in every morning, sticky in his Spider-Man pyjamas and cuddle me beneath the covers. I want to tell them about the time he jumped in a fountain that he thought was shallow and went in up to his neck, and the other time when he flooded the house because he wanted to go swimming. That to give him, a young man, a bath is a gentle humbling experience. That I love him with a fierce protectiveness that is almost painful, the way I imagine you love your own child. That I miss him. That it has been hard, but that he is happy.

But I rarely say all this. "No," I say instead. "He's not very good at maths." And then I try to change the subject.