“Do they know they’re adopted?” For eight years our unlikely family — an ageing white American mum and two impossibly lithe and beautiful adopted Asian daughters — lived in the country that could not keep them: China. And for all that time, the taxi drivers, the pedicurists and the trash-pickers of China wanted to know whether my children knew I had not birthed them.

Even the old Shanghainese lady eating Swedish meatballs in the Ikea cafeteria in Shanghai had to have the whole story of their lives — abandoned at birth, on a Chinese roadside, in winter, adopted by a single parent in her mid-forties, taken to live in Shanghai at age seven and eight — before she could get on with her supper. Always, the questions came sotto voce, in case the children had perhaps not noticed up to then that their hair was straight and black while mine was curly and grey, and our skin tones could not possibly have been produced by the same gene pool. Cross-racial adoption isn’t the kind of thing that anyone can keep secret for long, but most of China seemed willing to believe that I had somehow managed it.

Families like ours may look different but we are far from unique: everyone seems to know somebody who at least knows somebody who adopted a child of a different race. China alone sent well over 100,000 children, most of them girls, into overseas adoptions, mostly in the first decade of this century.