During the Second Boer War, Marais’s paternal grandmother was the leader of group of Boer women who for 18 months roamed about the western Transvaal and western Free State with their young children so as to avoid capture by British forces. His father, Jaap Sr., and paternal grandfather, Sarel Jacobus Stefanus, did active service on the Western front with the Bothaville commando. Both were made prisoner of war after Boer general Piet Cronjé’s surrender at the Battle of Paardeberg. Father Jaap Sr. was sent to Broadbottom Camp at St. Helena, whilst grandfather Sarel was held het Green Point, after which he received "parole" due to illness. He died a month after the end of the war. Marais’s mother, together with her mother and siblings, was interned at the Klerksdorp concentration camp.