Switching people like that, at an early age, can lead to dyslexia and other learning disabilities. I tend to believe that's why the rate of dyslexia is higher in lefties. It wouldn't affect a young adult or older person as much if they had to switch due to injury or stroke. It would be very frustrating, though.
As far as I know, Western countries don't actively switch kids anymore. Don't know about the rest of the world.
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