Had a co-worker that's so gullible that she thinks being left handed is bad based on the superstitions she's heard so she tried to convert her son. I told her don't believe in those superstitions because there's no valid proof and factual evidence to back it up. In fact being left handed is unique and highly sought in certain highly paid profession i.e., baseball, football, etc.
I explained to her that bias against left-handed people dates back to thousands of years, cutting across cultures all around the world. For instance, lefties in the Middle Ages were accused of practicing witchcraft, which then bore an infamous reputation.
Here's a superstition with zero proof to back it up:
“The Devil himself was considered a southpaw, and he and other evil spirits were always conjured up by left-handed gestures,”