It's fascinating that, at one point or another, most societies, from Arabs to Romans to Inuits, seem to have been leery of the southpaw in their midst. Arguably, we were the first minority, the first "other" in our communities, as Ben Franklin adroitly pointed out in "A Petition of the Left Hand":

I address myself to all the friends of youth, and conjure them to direct their compassionate regards to my unhappy fate, in order to remove the prejudices of which I am the victim.  There are twin sisters of us; and the two eyes of man do not more resemble, nor are capable of being upon better terms with each other, than my sister and myself, were it not for the partiality of our parents, who make the most injurious distinctions between us.

I'm very thankful to exist in a place and time where left-handedness has been stripped of much of the stigma and superstition that used to accompany it, and still accompanies it in some places. Still, I think I just scraped by at the end of that era, having memories of a kindergarten teacher handing me the right-handed scissors and insisting to me, "You're right-handed!" I thought that to be a simple factual error, and protested, not knowing what the big deal was.

From Fox News: "What Makes a Lefty: Myths and Mysteries Persist"

Lefties have long suffered. In India and Indonesia, as well as in most Islamic countries, eating with the left hand is considered impolite.

Chinese characters prove extremely difficult to write with the left hand. Not so long ago, teachers slapped the wrists of left-handed American elementary students.

Humans have shown the ability to learn to use their non-preferred hand after injuries, when required to perform manual labor, or in the face of cultural pressure.

Yet preference for handedness appears to take root in the womb, or even earlier.

...

Brain damage from trauma in the delivery room is another explanation.

"Proud lefties cringe at the thought of it," said the left-handed Wolman.

"The genetic model has wider support among the laterality community than brain damage at birth or levels of hormones in the womb," Wolman said. "At the end of the day, everyone seems to go back to the gene."

Yeah, let's go with the gene...