Nor is it primarily the result of a rational choice (i.e., a systematic analysis of facts) that liberals become liberals. 

We’d like to believe that we adopt our political views rationally, only after careful consideration of the “facts.” That’s a pipe dream, however.  Jay Dixit’s article, “The Ideological Animal,” (published by Psychology Today) demonstrates that our political persuasion takes root well before the cerebrum kicks fully into gear.  There are deep triggers that lead individuals to crave one political ideology over the other.  For many of us, rational thought is post-facto justification.  As David Hume famously argued,

Reason is, and ought only to be the slave of the passions, and can never pretend to any other office than to serve and obey them.

Dixit’s arguments dovetail with Hume’s beliefs.  As Dixit argues,

We tend to believe our political views evolve as a result of rational thought, in that we consider arguments, weigh evidence, and draw conclusions. But the truth is more complicated. Our political preferences are equally the result of factors we’re not aware of—such as how educated we are, how scary the world seems at a given moment, and personality traits that are first apparent in early childhood. Among the most potent motivators, it turns out, is fear.

What else correlates with political leaning?  You won’t be surprised at some of these differences:

conservatives and liberals boast markedly different home and office decor. Liberals are messier than conservatives, their rooms have more clutter and more color, and