As an only child, I find that reading about sibling relationships – and living among people who grew up in them – is a little like contemplating a three-­dimensional rendering of a four-­dimensional hypercube: something that’s only comprehensible to me because of my partial perception of it. It’s useful to understand why my partner gets the tape measure out when I pour the wine at dinner, or how a given set of parents might have instilled drastically different traits into two or more of their children, but the felt reality of having or being a sibling is remote to me. 

So I reach for accounts of such relationships with curiosity. Edouard Louis has written a number of books about growing up gay and poor in the northern French rust belt. In Collapse, he casts a cold eye on the story of his older half-brother – unnamed, like all the family members in the book – who drank himself to death in the twilight of a chaotic, violent and destructive youth. The reader is swiftly counselled not to expect anything too cuddly: 

I felt nothing at the announcement of the death of my brother: not sadness or despair or joy or pleasure. I received the news as one would receive information on the weather, or would listen to any random person relating their account of their afternoon at the supermarket. 

A few