Nothing that dramatic:
Dresie and Casie, Twins, Western Transvaal, 1993, in the book Ballenesque, Roger Ballen: A Retrospective
"Casie and Driesie, the twins, were mutes, with the mental capacity of five-year-olds, according to a psychiatric assessment record. The twins could not hold their saliva, and therefore drooled uncontrollably, and had to dry their chins with handkerchiefs they always carried in their hands. While they looked ‘unpleasant’ they won somehow managed to win the hearts of the staff at the nursing home they took residence in. They were free-spirited and could hug everyone that they came across, including the nurses. Casie and Driesie were so jovial and could laugh all the time. Since they could not communicate with words, they used grunts to try and pass a message to someone.
"Nevertheless, Casie and Driesie were skillful and could help around the nursing home. “Driesie spends most days knitting and Casie mostly sweeps in front of the stoop,” the manager of the home the twins stayed reported. “And on days when they just want to sit around, they just sit around.” It seemed the twins had a great bond between them, after all, they had lived their entire lives together.
https://publicdelivery.org/roger-ballen-twins/#Twins
Well, thank you for clearing that up. It’s been a rumor for a long time.