Re: ¿Porque tantos escépticos no queremos tener hijos?

Behavior Genetics and God

Behavior geneticists attempt to tease apart the relative roles of heredity and environment on any given trait. Since there is variation in the expression of all traits, we are looking for a percentage of the variation accounted for by genes and environment, and one of the best natural experiments available for research are identical twins separated at birth and reared in different environments. In one study of fifty-three pairs of identical twins reared apart and thirty-one pairs of fraternal twins reared apart, Niels Waller, Thomas Bouchard, and their colleagues in the Minnesota twins project looked at five different measures of religiosity. They found that the correlations between identical twins were typically double those for fraternal twins, and subsequent analysis led them to conclude that genetic factors account for 41 to 47 percent of the observed variance in their measures of religious beliefs.9

Two much larger twin studies out of Australia (3,810 pairs of twins) and England (825 pairs of twins) found similar percentages of genetic influence on religious beliefs, comparing identical and fraternal twins on numerous measures of beliefs and social attitudes. They initially concluded that approximately 40 percent of the variance in religious attitudes was genetic.10 These researchers also documented substantial correlations between the social attitudes of spouses. Because parents mate assortatively (like marries like because “birds of a feather flock together”) for social attitudes, offspring tend to receive a double dose of whatever genetic propensities may underlie the expression of such attitudes. When these researchers included a variable for assortative mating in their behavioral genetics models, they found that approximately 55 percent of the variance in religious attitudes is genetic, approximately 39 percent can be attributed to the nonshared environment, approximately 5 percent is unassigned, and only about 3 percent is attributable to the shared family environment (and hence to cultural transmission via parents).11 Based on these results, it would appear that people who grow up in religious families who themselves later become religious do so mostly because they have inherited a disposition, from one or both parents, to resonate positively with religious sentiments. Without such a genetic disposition, the religious teachings of parents appear to have few lasting effects.