Viscount Falkland
Hayes was baptised on 2 April 1676. He was the eldest son of Sir James Hayes and his wife Rachel née Hungerford, daughter of Anthony Hungerford. Rachel was the widow of Henry Carey, 4th Viscount Falkland. This Anthony Carey, 5th Viscount Falkland was Hayes' half-brother. Around April 1709, Hayes married Elizabrth Ashburnham, daughter of John Ashburnham, 1st Baron Ashburnham.