None has been provided, and Private User has found births registered to a Jan Harmse Steenkamp and Johanna Helena du Plessis – BUT they are dated to the late 1700s / early 1800s!
Unlinking these parents, pending primary sources.
cf Johanna Helena Steenkamp. Smit
Johanna Helena
Baptised: 1.4.1793
Father: Jan Harmse STEENKAMP
Mother: Johanna Helena DU PLESSIS
Source: Nederduits Gereformeerde Gemeente (NGK), Graaff-Reinet, Baptism register, 1792-1805, page 15, entry number 167. Repository: NG Kerkargief, Noordwal-Wes, Stellenbosch. Transcribed by Cornel Viljoen, with consent of the NGK Archives, from Family Search Film # 008121018, image number 20
https://www.eggsa.org/bdms/Baptisms.html