For conservatives in the country, liberal has become a kind of 7-letter dirty word - synonymous with loose-spending, morally corrupt, aggressive and deceptive. Of course, for those who identify to some degree as liberal or liberal-leaning, the word is reflective of positive traits such as open-mindedness, tolerance and social change. Hence, the synonym often used of “progressive.”  

Whether or not liberal political leanings (like conservative leanings) reflect underlying or inherent personality or biological characteristics is a point of disagreement and conversation lately.

Rather than reflecting a set of core characteristics, Jacob Hess argues that "every human being has a conservative impulse and a liberal impulse - on one hand, an impulse to hold on, preserve and conserve that which they find good - and on the other hand, an impulse to question and move past things they find insufficient in some way."  Rather than classifying folks into binary labels, then, the question becomes understanding what exactly people want to hold onto - and what they want to jettison. When it comes to the various Judeo-Christian traditions, for example, liberals and conservatives often sharply disagree not only on how to understand those traditions but also on which parts of those traditions they wish to retain, and which parts they wish to move beyond in some way.

Confusingly, the term “liberal” meant “supportive of free markets” until the 20th century and still refers to pro-market parties in Europe and most of the rest of the world today.  Thus a “classical liberal” in the U.S. is a libertarian or a “liberal” in Europe, i.e. an advocate of voluntary and market solutions to social problems.