Clark was born to an Irish Catholic mother and a Scottish Presbyterian father in Scotland. When she was two years old, her family moved to Malaysia where she and her sister attended an English school run by French nuns. At the time she also learned Malay. The school they attended in Malaysia was located in Bukit Nanas, Kuala Lumpur. When she was twelve years old, the family moved to Ireland where she attended the Muckross Park College in Dublin. In 1964, Clark began studying at the University of Lyon where she obtained a diploma in French language.
