Zinnie Harris is reviving Caryl Churchill’s A Number for the Edinburgh International Science Festival, a charged reflection on identity sparked by a son’s realisation that he is actually a clone of his father’s first child. The story is lent extra poignancy now that British scientists have been given permission to target genetically modified diseases through IVF (popularly referred to as cloning by a panic-stricken press in the nineties). The play raises important questions about the ethics of alternative reproduction and what makes us human, but offers no easy answers in the end.

Harris’s production resurrects A Number’s original set by putting the action inside a box, this time painted white rather than made of glass. The result gives the same impression of a sterile laboratory, one that contrasts sharply with the heightened emotions on stage and questions the traditional distinction between science and feeling. It also evokes the neglectful childhood that the first son suffered. Damask wallpaper has been painted over as if there was once potential for a warm and happy home, but the father has left their flat bare and uninviting.

Perhaps in tribute to Churchill’s experimentation with Brechtian theatre, the audience is forced out of its reverie periodically by a harsh blue light and explosive sound effects. Each detonation accompanies the arrival of a new clone for the father to speak with, so it is as if identity itself is blown off the stage with a cool clinical bang. You can imagine the individual ego exploding into tiny pieces.

After a tragic encounter between his first son and the clone that he raised, the father visits a second clone, Michael, to seek answers about selfhood. Where the other members of his family suffer an existential crisis at the thought that they are not “one”, Michael seems remarkably comforted by the fact that he is not individual. When pressed to delve deep inside himself to give his father a feeling that is unique to him, Michael relates stories about his own child, pieces of history that he finds interesting, minute details that he has noticed about his wife. Through his self-assured and mild-mannered stories about his life, Churchill suggests that our identities are formed by our relationships with the world around us. DNA goes so far, but inevitably our positive and negative experiences, childhood memories, and bonds with our family have an impact on that genetic destiny.