Nicholas Tuite MacCarthy was the second son of the eleven children of Count Justin MacCarthy of Toulouse (18 August 1744 – 1811), who was born at Spring House, near Bansha in County Tipperary and Maria (Mary) Winifred Tuite (September 1747 – 1822), daughter of Nicholas Tuite of St. Croix having relocated from the island of Montserrat. Nicholas Tuite MacCarthy's uncle, Robert Tuite, was chamberlain to the King of Denmark. His maternal grandfather, Nicholas Tuite of St. Croix, was the son of Richard Tuite of Tuitestown in County Westmeath. It was this Richard who fled Ireland as part of the Wild Geese in 1691 following an extraordinary family background in Ireland. Richard was one of only two surviving sons (the other being Robert) of Walter Tuite of Tuitestown and his wife, Margaret O'More, daughter of David O'More of Portallen in County Laois. Richard's remaining eleven brothers, Nicholas Tuite MacCarthy's great-granduncles, were all killed in the wars in Ireland in 1691.