The confident, resilient, self-reliant kids mostly grew up to be confident, resilient, self-reliant adults. It is the researchers' own bias and wishful thinking that leads them to believe that the definition of a "liberal" is a confident, resilient, self-reliant adult, when it is evident to everyone else that the liberal is a whining, insecure adult.
It is this very insecurity that explains why they are trying to justify themselves with this so-called scientific study. The qualities of "liberal" and "conservative" are never defined explicitly -- but implied from the liberal's own wishful thinking to regard themselves as possessing positive and healthful qualities -- while imputing negative and unhealthy attributes to those who don't see them that way.
Only liberals would think up a study like this -- to address their own appalling sense of inferiority -- which is not merely a complex but the real McCoy!
Talk about insecurity -- they wrote the book!
Obviously, people who dedicate and devote their entire lifetime to proving their own moral and intellectual superiority to everyone (anyone) else, doesn't have anything going for them.
It is obvious "liberals" dedicate their lifetimes doing.