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 Dr. Charles William MacCarthy and his spouse Marion. She spent her formative years in Sydney, Australia, after the family relocated there in 1885.