Edith Stoney was born at 40 Wellington Road, Ballsbridge, Dublin ; the daughter of George Johnstone Stoney, FRS, an eminent physicist who coined the term electron in 1891 as the ‘fundamental unit quantity of electricity’, and his wife and cousin, Margaret Sophia Stoney. One of her two brothers, George Gerald, was an engineer and a Fellow of the Royal Society (FRS). One of her two sisters, Florence Stoney, was a radiologist and received an OBE. Her cousin was the Dublin-based physicist George Francis FitzGerald FRS (1851–1901), and her uncle Bindon Blood Stoney FRS was Engineer of Dublin Port, renowned for building a number of the main Dublin bridges, and developing the Quayside.