Preface: When I was a young kid (2 years old), my mom decided that I should go to one of the many private preschools around the town. I ended up going to a Methodist preschool that was a few blocks away (my family is not Methodist, they just had really good reviews). Anyway, as a child, I was always left-handed. I did everything left-handed, and my family made no move to correct it. I've read some terrible stories of people trying to 'correct' their child's left-handedness.
So, I had just turned two, and was off to my first day of preschool. I don't really remember anything, besides stories that I heard from my parents, but my run-in with the 'teachers' there (and I use this term lightly. They weren't actual teachers, just people who volunteered) did not go down very well. They decided right off the bat that my left-handedness was a sin, and needed to be corrected lest I die and go to Hell (actual words from them).
They brought on their reign of the worst things they could. I was forced to only write with my right hand, and I was punished if I tried to write with the other one. It was, as my parents described it, one of the worst situations of my young childhood. But, I can give them credit for one thing, they did their job well.
I'm now right-handed, but can still write fairly clearly with my left hand. I've read quite a few articles on the psychological effects of being forced to write with your non-dominant hand. So, I'm attempting to relearn how to write with my left hand (at an acceptable pace, and readability), and then hopefully switch back to writing with that hand.