Dominance.

Being left handed can be like introducing yourself as the alien that no one can really trust. I went to catholic schools, after the days when they used to tie your left arm behind your chair, happened to my nan, trying to force the left from you. Though those days were gone, there was always a feeling that I wasn't quite right, or it could have been that sister Ann who taught me for two years, couldn't stand me. 5 through 7, great days. Being left handed is very useful in some sports, cricket and baseball particularly.

 Normal jobs? can be a bit bollocky. Can't be an electrician, death and such. My dental hygienist, who is left handed, had to learn right handed. It makes a major difference having a left handed dental hygienist. Anybody who is left handed could tell you why. That's why right handed people look upon us with suspicion.When you tell them, "It's just different," eyes narrow, and torches begin to burn behind their eyes. The most left handed people you will find gathered together are in the arts. Why is that? Is it some dark connection to the unknown? No, its because the arts are a place where the hand you write with doesn't matter. 

This came up, as I'm researching hand / eye dominance and its effects on dyslexia. The effect having a dominant right eye whilst being left handed, or the reverse, has on learning skills. They talk about patching an eye until the dominant is back in control. Sounds like strapping your arm behind a chair to me.