In the book of Judges, we learn that the tribe of Benjamin fielded a corps of slingers. 

These soldiers were not mere conscripts, but rather we're informed that they were "chosen", in the sense of 'elite' or in some way elevated to a position of esteem. Moreover, they were skilled at the sling to the extent that they were accurate to a hair's breadth.

What's more interesting is that this corps of chosen elite was left handed. How did this come to be? Were these soldiers veterans whose right arm had become mangled and disfigured during the course of so many campaigns such that it was no longer usable? And so they retrained into left handed slingers? And having been veterans they were already combat-ready and disciplined and thus ready to be a "chosen" elite?

Or were left handed children culled at a very young age and trained to be slingers (i.e., the Jedi model)? If so, how could there be so many left handed children so as to make a "chosen" corps of 700? 

Otherwise what is a plausible explanation for an elite corps of left handed soldiers?