She grew up in a Jewish family, with ancestors who moved to the UK from Belarus and Poland. Margolyes was born in Oxford on, the only child of Joseph Margolyes (1899–1995), a Scottish physician and general practitioner from the Gorbals area of Glasgow, and property-developer Ruth (née Walters 1905–1974), daughter of a second-hand furniture dealer and auctioneer at Kirkdale, Liverpool, who later relocated to London.
