There is a continuity problem in the early Tarzan novels, since Burroughs has not allowed enough time in the series for Korak to grow up. Tarzan fans haved traditionally solved the problem either by altering the chronology of the early books (following the theory of Peter Ogden, editor of ERBania), or by making Korak into an adopted son of Tarzan (per H.W. Starr and John Harwood).
In Tarzan Alive, Philip José Farmer considers that this latter option is the correct one, citing the appearance of a 'youthful Jack' in Burroughs's The Eternal Lover as indicating that Tarzan and Jane's biological son John Paul Clayton, Lord Staveley is a separate person to Korak.
According to Farmer, Korak's full given name was John Drummond-Clayton, and that he was actually the brother of Bulldog Drummond, adopted on the deaths of their mother and father (both the Drummonds and the Claytons can trace their descent from witnesses to the Wold Newton Meteorite strike). Korak and Meriem were the parents of John Armand Drummond-Clayton.