What makes people vote the way they do? Why, in the words of Gilbert and Sullivan’s “Iolanthe,” does “nature contrive” that babies are born either “a little liberal or else a little conservative”? In the American election of 2000, the voted was divided almost evenly between two candidates whose differences on conservative-liberal issues were as clear as it gets in American politics. Today, those differences and the closeness of the contest seem even more pronounced.

Why do voters separate so evenly along these liberal/conservative lines? What clues do we have to the origin of their differences? As someone who has rung doorbells, shaken hands on bus lines and, as a state senator for 20 years, answered the mail, I can tell you that it is only a matter of minutes for a working politician to sense some hidden signals at work.

It is not enough to say that voting choice can be determined by economic, ethnic, and social self-interest. Culture, class and special interest are, of course, powerful motivators and those identities are where any politician invariably starts. But how voters interpret their cultural and group identities and, for that matter, their own self-interest is in many ways the product of those unspoken premises that somehow divide voters into liberals or conservatives.

More importantly, we know that people within the same economic, cultural, or social group with the same “self-interest” can differ intensely in their politics. Indeed, such people comprise the crucial “swing voters” that we hear about so constantly. These swing voters are influenced to a substantial degree by the latent premises they bring to their electoral choice and it is critical to understanding American politics to identify those premises.

Today, genomic science is focused on the sources of human motivation. Success in sequencing the human genome – that is, unraveling and mapping the DNA that contains and directs our genetic tendencies – is about to tell us more than we may want to know about our inner selves, including the predictability of our political choices.

We are told, for example, that identical twins separated at birth show a +.62 correlation from -1 to +1 in liberal/conservative temperament. Identifying and differentiating those genetic elements should tell us how nature does, indeed, contrive to divide those babies into liberals and conservatives.

Pierre Teilhard de Chardin observed that political activity can only be understood in terms of “the whole phenomenon of man.” That phenomenon is about to give up some of its most closely guarded secrets.

We already have some important clues to what we should expect to find. Geneticists and anthropologists have identified genetic traits in human development that tend to liberal or conservative preference. In “The Blank Slate,” Steven Pinker points out the superficial differences: In the most euphemistic sense, liberals tend to be more beneficent and optimistic in their view of human nature while conservatives tend to be more conscientious, traditional, and authoritarian.

Are these heritable and therefore genetic traits? If so, as Mr. Pinker goes on to say, “the heritability of political attitudes can explain some of the sparks that fly when liberals and conservatives meet.” In other words, those bitter arguments across the dining room table are not really about politics, but about identity itself.

Can these heritable political “genes” be isolated and studied in the same way as the genetic source of various diseases can be isolated and studied? If so, they could theoretically be studied and analyzed with the ostensible view of producing a “better world” depending, of course, on the point of view of the geneticist.

Geneticists at Harvard are at work today on ways to map the “personal genome,” with the view in mind of enabling each of us to under stand and hopefully improve our physical and emotional selves. This analysis would surely include the disclosure of underlying “political” premises and preferences.

Politicians and political consultants constantly attempt to penetrate the splendid disorder of American politics with its outrageous sound bites and insidious political advertising in order to discover and appeal to the inner premises that divide those Gilbert and Sullivan babies into liberals and conservatives.

Whether it is desirable or effective to reduce these premises to their genetic source, the tools for doing so are here. The question is not whether or not they should be used, the question is how they will be used and who will use them.

Mr. Bronston served as a Democrat in the New York State Senate from 1958-78, where he led the debate on educational finances in New York State. He is a magna cum laude graduate of Harvard College and a graduate of Harvard Law School. He served in U.S. Marine Intelligence during World War II. He currently practices law in New York City.