Sometimes the Most Obvious Answer is the Right Answer

The Toronto Star has a story on research on children's tendency to grow up liberal or conservative based on how they behaved as children. The study began in the 1960s and tracked 95 kids. The basic result? Whiny children grow up rigid and traditional, becoming junior Republicans. The confident, resilient and self-reliant kids? Well they grew up to be liberals. The researchers hadn't started out looking at political orientation, it became part of the record keeping as the study progressed and the young adults began defining their beliefs.

From the Star:
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.

The reporter also notes that:
Of course, if you're studying the psychology of politics, you shouldn't be surprised to get a political reaction. Similar work by John T. Jost of Stanford and colleagues in 2003 drew a political backlash. The researchers reviewed 44 years worth of studies into the psychology of conservatism, and concluded that people who are dogmatic, fearful, intolerant of ambiguity and uncertainty, and who crave order and structure are more likely to gravitate to conservatism. Critics branded it the "conservatives are crazy" study and accused the authors of a political bias.