These study results are really interesting:

In the 1960s Jack Block . . . began tracking more than 100 nursery school kids as part of a general study of personality . . . A few decades later, Block followed up with more surveys, looking again at personality, and this time at politics, too. The whiny kids tended to grow up conservative, and turned into rigid young adults who hewed closely to traditional gender roles and were uncomfortable with ambiguity.
The confident kids turned out liberal and were still hanging loose, turning into bright, non-conforming adults with wide interests. The girls were still outgoing, but the young men tended to turn a little introspective.
. . .
In a society that values self-confidence and out-goingness, it’s a mostly flattering picture for liberals. It also runs contrary to the American stereotype of wimpy liberals and strong conservatives.

(via Follow Me Here)