John Charles JESSON was a son of Thomas JESSON (1810 - 1871) and his wife, Anne Frances KEMP (1825 - 1869). Anne Frances KEMP was the youngest daughter of Thomas Read KEMP (23 XII 1782 - 20 XII 1844), MP (Whig) for Lewes, 1811-16, for Arundel, 1823-26, and again for Lewes, 1826-37; her mother was his first wife, Frances BARING (1783 - 8 III 1825), daughter of Sir Francis BARING, 1st Bt (18 IV 1740 - 11 IX 1810) and his wife (married 12 V 1767), Harriet HERRING (1750 - 1804).
John Charles JESSON had a brother, Thomas JESSON (1850 - 4 III 1928), who was married, on 16 June 1875, to Charlotte Anne THICKNESSE-TOUCHET (1849 - 1 III 1912), who was a granddaughter of the 20th Baron AUDLEY; their grandson, Thomas Percy Henry TOUCHET-JESSON (15 IX 1913 - 3 VII 1963), succeeded as the 23rd Baron Audley on 27 May 1942.