[1] Gerald FitzMaurice was born in Wales in about 1150, the second-eldest son of Maurice FitzGerald, Lord of Llanstephan by his wife, Alice (daughter of Arnulf de Montgomery).

[2] Gerald had one sister, Nesta, who was named after their celebrated grandmother, Princess Nest ferch Rhys, and five brothers, including the eldest, William FitzMaurice, 1st Baron of Naas.

Gerald's father was the leader of the first landing of Normans who arrived in Ireland in 1169 to assist the exiled Irish king of Leinster Dermot MacMurrough regain his kingdom.

[3] Accompanying his father from Wales to Ireland, he and his brother Alexander showed great valour in the battle against Roderick O'Conor outside the walls of Dublin in 1171.

Upon the death of their father, on 1 September 1176, Gerald's elder brother William granted him half the cantred of Ophelan with centres at Maynooth and Rathmore.

William FitzAldelm deprived Gerald and his brothers of their stronghold of Wicklow, though, after a time, was compelled to give them Ferns in exchange.