Writing about one's children is a risky business. But authors' parents? They've long been fair game. Doris Lessing, however, has decided to rewrite the script in this blend of fiction and memoir, imagining how her parents' lives would have been had they never married and - more significantly - had their generation been spared the First World War. What is impressive is the insight and integrity with which she pursues these alternative lives, resisting the temptation to remedy every grief. Understandably so, for the couple to whom she was in reality born seldom seemed to notice, let alone satisfy, her needs. The sense is of an ongoing, personal ontological struggle driven by that failed child's demand: "But why?"

Doris Lessing's half-fiction, half-memoir is a clever example of just how sharply counterfactual history can illuminate life's wrong turns and paths not taken. What if her parents had met but never married? That Lessing would not exist is not her point here, though it is one that the reader cannot avoid. Rather, she allows her father, Alfred, to move contentedly through an eternal Edwardian summer of cricket and gentle English farming; no war to break his health, no rash emigration to Rhodesia with a disappointed wife. For her mother, Emily, nursing and a loveless marriage provide opportunity and means to become a philanthropic educationalist with money to spare for elegant clothes. Yet there is no gain without loss: an England without the first world war and with all its Edwardian hierarchies intact is still troubled, and contentment is hard won for both Alfred and Emily. Lessing's hybrid is a beautiful, wise reflection on how we simultaneously embroider and unpick our parents' lives in an effort to understand ourselves.