Capito came from a plebeian family whose members had reached the rank of praetor since the 2nd century BC, but none had achieved the consulate until the end of the republic in 33 BC, when Gaius Fonteius Capito acceded to that magistracy. According to Cicero, the Fonteii came from Tusculum. Capito was probably the son or grandson of the eponymous consul of the year 12; his brother Fonteius Capito was one of the consuls of the year 67.
- Paul A. Gallivan, "Some Comments on the Fasti for the Reign of Nero", Classical Quarterly, 24 (1974), p. 291, 310
- Friedrich Münzer, "Fonteius", Realencyclopädie der classischen Altertumswissenschaft (Stuttgart, 1909), volume VI,2, col. 2841
- Cicero, Pro Fonteio, 41 (31)
- Alfred Kappelmacher, "Fonteius (22)", Realencyclopädie der classischen Altertumswissenschaft, volume VI,2, col. 2848