Why Am I Left-Handed?

For me it's as if I'm missing a muscle in my right hand. I can do the Vulcan salute just fine with my left, but not at all with my right. I simply don't have the same input responsible for that specific motion. I have no trouble typing with both hands or doing most tasks, as we're adaptable, but it's still a physical limitation.

Here's an experiment - place both of your hands flat down on your desk, and on each hand try to tap your ring finger on the surface without lifting or moving any of the other fingers. I can do this hard enough to make a noise with my left, but not with my right.