In my case I actually favored my left hand as a toddler but my mother forced me to use my right hand for everything. This was a common practice at the time because of the limited availability of left handed products for consumers, i.e. scissors, baseball mitts, guns, etc.. As I got older I learned that it was not very difficult to learn to do things with my left hand, a little practice and I had it. I assume this shallow learning curve is the result of me having been born favoring the left hand to begin with.