Pares was born at the family home at 12 Devonshire Gardens, Portland Place, London, the eldest son of John Pares (1833–1915) and Katharine (née Back). His father was the son of
Thomas Pares (1790–1866), who was
M.P. for
Leicester from 1818 to 1826. His mother was the sister of Admiral Sir
George Back FRS (1796–1878), the explorer and naturalist. Pares was one of ten children of the marriage between John Pares and Katharine; he had four brothers (George (Lancelot), Bernard, Basil and Howard) and five sisters (Alice, Ethel, Margaret, Constance and May). His brother,
Bernard (1867–1949), was a historian and academic known for his work on Russia. On 22 August 1888, he married Beatrice Emma, daughter of William Ireland Blackburne. ==Career==