Gary Stevenson was born in 1986 in Ilford, a large town in East London, historically part of Essex but now incorporated into the London Borough of Redbridge. Ilford during the 1980s and 1990s was a predominantly working-class area undergoing demographic and economic changes as London expanded eastward. This environment would shape Stevenson's early understanding of class and economic dynamics in British society.
Stevenson was the middle child of three siblings in a typical working-class family. His father worked as a post office worker, a stable but modest occupation that placed the family firmly in Britain's working class. Details about his mother's occupation have not been prominently featured in public accounts of his life, but the family background was certainly not one of privilege or wealth.