His father Edward Thornton Littlewood was also a mathematician and was Ninth Wrangler in the Mathematical Tripos at Cambridge in 1882, three years before his eldest son John Edensor was born. Edward and Sylvia Littlewood went on to have three sons, their second being Martin Wentworth Littlewood, who went on to study medicine, and a third son who tragically died when he was eight years old by falling into a lake from a bridge.
Kanyang ama Edward Thornton Littlewood ay din ng isang dalub-agbilang at noon ay ikasiyam Wrangler sa matematika Tripos sa Cambridge sa 1882, tatlong taon bago ang kanyang anak na lalaki diko John Edensor ay ipinanganak. Edward at Sylvia Littlewood nagpunta sa may tatlong anak, ang kanilang pangalawang pagiging Martin Wentworth Littlewood, na nagpunta sa pag-aaral sa mga gamot, at ang isang ikatlong anak na lalaki na tragically kapag namatay siya ay walong taong gulang sa pamamagitan ng pagbagsak sa isang lake mula sa isang tulay.