His mother Myrtle May ALLEN married in 1924 to Konrad ELIES (b. 1889 SA, d. 1964 SA). She died in 1962.
Note Jesse's birth was also registered as ALLEN (it may have been re-registered as DRUMMOND as part of the adoption process).
ALLEN Jesse Clement Pettmann
[mother] Myrtle May ALLEN
I wonder if 'Pettmann' is a clue as to the identity of his father???