One of the most intriguing questions regarding personal religiousness and spirituality concerns why some people are more motivated than others to seek and find a faith perspective. For many, this raises the question of whether nature (for example, genetics) vs. nurture (for example, upbringing) makes more of a difference.
Psychologists often use behavioral genetics research to try to untease the relative effects of nature vs. nurture.
For instance, in one large study, approximately 2,000 identical twins and 2,000 fraternal twins born in Virginia were asked questions about their religious values, church attendance, and religious affiliation. Identical twins were considerably more similar to each other in their values and attendance, but not so much in their affiliation. Research conducted at the University of Minnesota comparing identical and fraternal twins raised apart (in separate home environments because of being split apart through the adoption process) suggests something similar with the extent to which individuals report being intrinsically religious (whereby they pursue religion because they sincerely believe). Taken together, this line of research suggests that one of the main reasons why individuals differ in strength of religiousness (but not affiliation) is because of their genetics. Similar to mental illness, intelligence, and personality, it seems that there is some kind of predisposition to being relatively more or less religious, with estimates suggesting that 30-50% of differences in personal religiousness is due to genes.
What does this mean? Some have suggested that this “explains away” the need to assume that there is a real God, the idea being that the primary motivating force behind religious belief is genetics. This fits well with naturalistic evolutionary accounts suggesting that religious belief came to our species because of its’ adaptive value. Similar arguments have been made because of research showing that particular parts of the brain seem to be most involved in particular kinds of religious or spiritual activities (such as meditation or deep prayer).
However, this research does not say that religiousness or spirituality is “genetic.” If it was, 100% of the variation among people’s religiousness and spirituality would be due to genetics, not 30-50%. The best estimate we have is that 50-70% of the differing levels of strength of religious and spiritual beliefs across individuals seems to be due to non-genetic factors.
Contrary to the notion that such research “explains away” God, these studies actually reinforce some of my spiritual inclinations. That is, this research seems very consistent with the idea that people have spiritual gifts, one of which is “faith.” Some people likely possess a personality that is more amenable to faith, perhaps because of openness or humility, whereas others more naturally question and doubt, are closed to religious and spiritual notions, or desire more personal control of their lives. For instance, I am naturally drawn to questions of faith; others seem to care less. Part of this must be due to a natural difference among people that motivates or doesn’t motivate a spiritual quest.