User blog comment:Cmreed21410/Shanks/@comment-46122084-20200815103302/@comment-108.83.222.210-20200815205338

It is apparently an old superstition. Some people believe that the devil is left-handed or something of that nature and thus they assume that those who share this trait are either evil or easily seduced by evil. Personally, it really makes no sense to me, but that is presumably where this conclusion comes from.