My father was left-handed, though he wrote with his right, having grown up in the time when children were forced to change to the majority standard. That's why this Post piece was interesting, looking at the distribution of lefties over time and modern lefties geographically. But the best writing on the subject I've read is still "Right Hand, Left Hand", a book by Chris McManus, who runs a blog here.
McManus in his book gets into some basic things, like how do we determine handedness at the most elemental level, molecules and atoms. (Left-handed sugar isn't absorbed by the body.) I won't pretend to have followed all the explanations, but he also gets into driving on the left versus driving on the right, and the genetic and environmental influences on fetal development.