That has been my position, at least until twin studies began to suggest that hereditary factors influence personality traits and that personality traits influence the choice of ideologies. It is important to emphasize, however, that those investigators whose findings suggest that genetic factors impact ideologies believe that they are but one piece of a complex interaction in which experiential variables usually dominate. The issue is not: Do genes determine ideologies; but rather: Do genes play any role at all?
The findings regarding both religious and political ideologies emerge from twin studies and focus most firmly on the conservative-liberal dimension of belief systems. There are problems both with twin studies and with this major focus. I will deal with them later. First, what are the findings?
Twin studies compare similarities and differences in monozygotic and dizygotic twins. If monozygotic twins are more alike than dizygotic twins, the interpretation is that genetic factors account for the difference, and the magnitude of the difference indicates their strength. Two of the better-known US twin studies included self-report measures of religious conservatism and found that monozygotic twins were significantly more alike in this characteristic than dizygotic twins.1,2 They concluded that genetic factors appear to play an appreciable role in the adoption of conservative religious beliefs. More recently, political scientists analyzed the data from one of these studies (involving 8000 sets of twins) and concluded that the conservative-liberal dimension of political ideologies also has a genetic component.3 Thus, it seems that we should, at a minimum, begin to take the question of genetic influences on ideologies with some seriousness.
If such influences operate, they most likely do so indirectly—that is, through the genetic impact on personality characteristics. In a more formal way, the proposition would be that certain personality characteristics are the mediators of the genetic influence on ideologies. This, of course, means accepting the premise that personality influences choice of ideology, and this proposition has its own up-and-down history. Jost,4 in a recent and thorough survey and integration of his own research and that of others, traces the history of academic psychology's phasic acceptance and rejection of the role of personality in determining political ideologies. He concludes that there is clear and mounting evidence that certain personality traits are associated with the conservative-liberal dimension of political ideologies. Although there is considerable variation among those who define themselves as either conservative or liberal, 3 of every 4 Americans will do so (self-defined conservatives are more than twice as prevalent as their liberal neighbors).
More to the point of this essay, however, is Jost's finding that certain personality traits are more often found in each group. Conservatives, for example, are more apt to demonstrate (again, by self-report) a propensity for order, structure, closure, conscientiousness, and tradition. Liberals more often define themselves as open to new experiences, creative, and more tolerant of ambiguity. Since twin studies have demonstrated that most (perhaps all) personality traits have a genetic component, we have a possible connection between genes and political ideologies.
There remain, however, significant questions. The first involves the twin methodology. Although this method continues to be broadly accepted, critics have questioned whether recruitment methods result in a representative sample of twins. Another is how much the twin methodology minimizes environmental influences by assuming, for example, that living in the same family means having the same environment. There is evidence that children in the same family may experience the family differently and that their views change over time. Finally, the results of twin studies only result in information about that particular sample of twins and cannot be safely generalized to other populations. There are other questions about twin studies, and so it seems wise to maintain some degree of skepticism if all the data about genes and ideology come solely from twin studies.
There are also questions about the use of the conservative-liberal dimension as a (or the) defining marker of an ideology. Whether doing so embraces an overly simple reductionism of much more complex phenomena (belief systems) is a reasonable question. Why not use, for example, complexity, level of integration, or change and stability over time? Looy5 has discussed this issue and others in her review of the implications of both evolutionary theory and behavioral genetics (twin studies) for faith (Christian). She comments that people of faith can be uncomfortable with the idea that their beliefs are rooted in their biology—as if something sacred is being degraded. The twin studies, she writes, provide only faint hints about a possible biology of religion. Looy is critical of the attempts to reduce the complexity of religion to easily measured variables and notes the conservative-liberal distinction as one such effort.
Another confounding factor is how the premise that genetic factors influence ideologies accounts for changes in ideology during the adult years. Although I am unaware of any longitudinal data, surely many persons' ideologies are changed (even reversed) by adult experiences. A now-deceased high school friend of mine is an example. He was the son of Sicilian immigrants, lost his mother when he was 3 years old, and developed an obvious compulsive personality structure that served him well in the world of commerce. Until he was well into his 60s he was a staunch conservative. Then he became increasingly dissatisfied with the outcome of local, state, and national conservative governments. After several years of struggle with this issue, he began to articulate a liberal ideology. "I can't believe what's happened to me politically," he said with obvious passion. "I've ended up endorsing all that I opposed all my life. It's incredible—but it really is the way I think now." He not only changed his political ideology but in the last 15 years of his life was active in causes usually identified with the liberal position.
My friend remained a fairly compulsive person. Order, structure, closure, conscientiousness, and tradition were obvious until the end of his life. I do not know, as I write this, whether my sense that he developed a greater tolerance for doubt and ambiguity, greater support for innovation (as, for example, in health care), and more concern about social inequities reflects actual changes in his personality or whether I was reading in such changes because they are supposed to mediate his ideological change.
One can reach out further into speculative realms by asking whether such changes reflect turning on or off certain genes and the growth of new brain circuits. With these and other obvious issues in mind, the question can be raised: What does all this have to do with clinical practice?
I would respond that at this point in time and with only the hint of a possible interaction between genes, personality traits, and religious and political ideologies, the major implication for clinical practice is in how clinicians think. For most of us, it likely is a challenge to broaden our theories of mental function—to allow for a greater variety of causative variables. In short, if these hints are expanded into a more solid database, we, as clinicians, need to become more flexible in our thinking. And that, we have much reason to believe, will impact how we understand and treat our patients.