In my own personal and subjective experience, the correlation between left handed people I know and "edginess"-level is almost 1.
I am inclined to believe this is a learned trait rather than an innate one (excluding the obvious reasons why one would be left-handed only).
I would suspect the causation (if such a correlation does exist) goes in the other direction (or more likely, has a common cause), given how early handedness tends to appear (and how it can be quite resistant to pressure to conform).
What?