MacCarthy was born in Clonmel, County Tipperary, Ireland, the daughter of Dr. Charles William MacCarthy and his wife Marion. Her early years were spent in Sydney, Australia, where the family emigrated in 1885.
MacCarthy was born in Clonmel, County Tipperary, Ireland, to a family that included her father, Dr. Charles William MacCarthy, and her mother, Marion. She spent her early years in Sydney, Australia, after the family made the move there in 1885.