I mostly use the mouse in my right hand, but that may simply be due the way most computers and workstations get set up. I'm pretty comfortable with either hand - although I prefer to use my right hand with the touchpad on my laptop.

Since experience, especially early experience, plays a big role in how the brain gets hardwired, it makes sense that lefties tend to be more ambidextrous in a world designed for right-handed people. Think of all the folks who had the crap beat out of their knuckles by an early teacher until they learned to use a pencil in their right hand. (I'm lucky my mother went to school after my first humiliating day and had a hissyfit in the principal's office.)



How many lefties here, especially those who are fairly ambidextrous, have not-so-good fine motor skills, despite lots of practice. (Think of handwriting or of activities like typing speed and accuracy, or playing an instrument really well.)