Left-Liberal And Conservative Attitudes Are Heritable
Liberal and conservative political attitudes are largely, though far from completely, heritable. When identical twins who were separated at birth are tested in adulthood, their political attitudes turn out to be similar, with a correlation coefficient of .62 (on a scale from -1 to +1).2 Liberal and conservative attitudes are heritable not, of course, because attitudes are synthesized directly from DNA but because they come naturally to people with different temperaments.
2. Personal communication, D. Lykken, April 11, 2001. Other estimates of the heritability of conservative attitudes are typically in the range of .4 to .5: Bouchard et al., 1990; Eaves, Eysenck, & Martin, 1989; Holden, 1987; Martin et al., 1986; Plomin et al., 1997, p.206; Scarr & Weinberg, 1981.
from "The Blank Slate: The Modern Denial of Human Nature"
Quoted on Sat Oct 8th, 2011