In his bestselling autobiography Dreams from My Father Mr Obama recalls how, during his first visit to Kenya, his cousin referred to an uncle, Omar, who had left Africa and moved to Boston, but had been “lost”. A little later in the book Mr Obama travels to the family village in western Kenya where he meets his step-grandmother, Sarah, the woman who had raised his father. On the walls of her tin-roofed hut, Mr Obama noticed photographs of the missing Omar, “the uncle who had left for America twenty-five years ago and had never come back”. The woman he calls...