STUDY: Confident, self-reliant kids grow up - liberals; Whiny Kids - Conservative

Basically, the jerks who like to disobey and cause trouble grow up to be liberals, and the kids who are respectable and listen to those in authority become conservatives. When they complain to the authority figure about a future liberal picking on them the liberal just calls them a cry baby and whines about a police state when they get tossed in detention.

This article was on Slashdot (pretty liberal) awhile back and the overall theme was that this report didn't make liberals look good.