 He was the son of T. P. Karthigesu, a Tamil pundit, and Valliammai.He was educated at Vigneswara Vidyalayam and Zahira College, Colombo (1949–52).After school Sivathamby joined the University of Ceylon, Peradeniya in 1953, studying under K. Kanapathypillai and graduating with B.A.