In 2005, Alford asked 9,000 identical and fraternal twins to agree, disagree, or express their uncertainty toward these three words and 25 others like them. Positive responses to half of the 28 items raise one’s conservatism score, and positive responses to the other half lower one’s score. Negative reactions do the opposite.
Alford’s twins considered these terms and wrote down their answers. Amazingly, for every single item, the identical twins’ political orientations correlated more strongly than they did for the fraternal twins. And in every case, the difference in strength was significant. Alford’s experiment and others like it consistently show that 40 to 60 percent of the variance in our political attitudes comes from genetic differences between individuals. The remaining differences come from environmental factors.
Alford’s findings suggest that the Blocks’ nursery school children weren’t inevitably predestined to become Republicans or Democrats. Nonetheless, their adult opinions on controversial issues ran even deeper than their childhood personality traits; a substantial proportion of their political dispositions stemmed from their genetic makeup.
Because our political attitudes have such deep roots, we don’t normally undergo radical ideological shifts later in life. As people pass through their thirties, forties, fifties, and sixties, their identities stay quite stable; when measured from one decade to the next, the average individual’s political orientation correlates very strongly with itself (at .80). Political attitudes do in fact change over time, but they change at predictable ages, and in foreseeable directions.
The Universality of Left and Right
The left-right political spectrum is universal. It forms a natural, bell-shaped curve—like height, weight, and blood pressure, but unlike income distribution. Some countries have wider or narrower spectra. But how can we know whether the left-right orientations of groups as a whole compare with one another? In other words, are the Blocks’ children as conservative or as liberal as their counterparts in Tunisia?
In psychology, there are a few standard personality traits that have been measured across truly diverse human groups. They belong to a well-tested and widely accepted inventory called the “Big Five” personality dimensions. Specifically, these traits are Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism (it’s easy to remember them because they spell out OCEAN). The first three dimensions (O, C, and—to a lesser degree—E) correlate fairly well with left-right voting. Therefore, these traits can serve as a universal yardstick for measuring the dispositions of disparate cultures, which would otherwise be difficult to compare in reference to specific political issues.
Psychologist Robert McCrae, with the help of his colleagues from numerous countries, has collected measures of these Big Five dimensions from nearly 28,000 people from 36 distinct cultures around the world. The participants represented the Indo-European linguistic family, as well as the Uralic (Finland, Hungary, Estonia, etc.), Dravidian (South India), Altaic (Turkic, Mongolic, etc.), Malayo-Polynesian, Sino-Tibetan, and Bantu (Sub-Saharan Africa) ethno-linguistic groups.