right handed vs lefthanded

It has something to do with the dominant part of the brain. Right handed persons use their left hemisphere more than their right, with the left handed persons it is the reverse. Although it is possible to switch dominant hand. A girl in my class was left handed when she was very young, but she learned to write with her right hand, so now she is right handed.

It's innate, but it can be changed too. Back then, people think that you're demon-spawn if you're a lefty, and so they would force you to write with your right, to the point of tying up your left hand. -_-"