[monooso]

Not my area of expertise, but this article appears to completely ignore several factors which were true when I was growing up as a leftie in 1970s UK (admittedly some time ago):

1. Some schools actively punished children for writing left-handed.

2. Pretty much every utensil was made for right-handed people. I don't recall ever seeing left-handed scissors, for example.

3. You learn by copying those around you. If your parents, teachers, and peers are predominantly right-handed (and are even actively encouraging you to be right-handed), then you're likely to toe the line.

I imagine the final point would remain a factor long after the first two are addressed.