In the notes of that post someone was listing different cultures views of left handedness and one that struck me was that they claimed Zulus burnt children's hands in hot water if they were left handed.
Now I dont know everything about every south african peoples but im 99% sure a culture which where shield and spear warfare and agriculture was important would not want to stop people from using both of their hands.
So I looked it up and found an article that mentioned this and linked to a paper. So I looked in the paper ctrl+F and searched Zulu... nothing. The closest was Zuni, who are a Native American tribe. Okay so maybe the author of the article Zuni and Zulu mixed up? Nope there's nothing about scalding peoples hands in regards to the Zuni either, in fact the Zuni believe the left side of the body to be the wise and intelligent side.
So I searched water... nothing. I searched burn... nothing. Its as if the writer of this article, a white woman, just made it up and thought that no one would look at the paper she looked at. Which people didn't do of course because people see "Zulu" and think "savages" and so can believe something like that without question.