John David Home Robertson was born at 18 Eglinton Crescent, Edinburgh, the son of John Wallace Robertson, Lieutenant-Colonel of the King's Own Scottish Borderers regiment, who assumed the additional surname in 1933, by Scottish Licence, of Home following his marriage that year to Helen Margaret (1905–1987), elder daughter and heiress of David William Milne-Home (1873–1918), of Wedderburn & Paxton, Berwickshire.