The left-right political spectrum is universal. It forms a natural, bell-shaped curve—like height, weight, and blood pressure - theatlantic.com
Figure 1 shows the correlations between the left-right orientations of twins raised together and apart. The black bars correspond to identical twins, and the gray bars to fraternal twins. The first two clusters show the twins raised together. Identical twins (who share 100 percent of their genes) had more similar political orientations than fraternal twins (who share only 50 percent of their genes, like normal siblings).
The third cluster shows the amazing finding of Bouchard’s survey: Identical twins reared apart had a strong correlation between their political orientations; but the scores of fraternal twins raised separately didn’t correlate significantly. These results suggest that genetics plays a decisive role in determining political attitudes. In other words, identical twins are more likely than fraternal twins to agree on divisive issues, precisely because they’re more closely related to one another.
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.
Variation in these Big Five personality traits is greatest within cultures. This finding makes intuitive sense, since a given population has a bell-shaped distribution of left-right political orientation. Moreover, Big Five dimensions such as Openness and Conscientiousness also form bell-shaped curves within a population.
In addition to the large variation within cultures, however, McCrae together with his colleague Jüri Allik also discovered small variations in personality traits between groups. |
