How Bizarre - Episode 12

Hands:

Every male in the Colombiere family of Nancy, France, was born with two left hands: both their hands had thumbs on the right side. They were perfectly normal in every other way. This trait only appeared in Colombiere males; females of the Colombiere family had normal hands.

So, my only question is, are they predominantly right-handed or left-handed? Because technically, they still have a right and left hand. Unfortunately for them, they just happened to both look exactly the same. I really wanna know. Do any of you know more about these guys?