New Scientist reports on the findings of a study on the impact of genes on religious inclinations
Genes may help determine how religious a person is, suggests a new study of US twins. And the effects of a religious upbringing may fade with time.
Until about 25 years ago, scientists assumed that religious behaviour was simply the product of a person’s socialisation - or “nurture”. But more recent studies, including those on adult twins who were raised apart, suggest genes contribute about 40% of the variability in a person’s religiousness.
But it is not clear how that contribution changes with age. A few studies on children and teenagers - with biological or adoptive parents - show the children tend to mirror the religious beliefs and behaviours of the parents with whom they live. That suggests genes play a small role in religiousness at that age.
Now, researchers led by Laura Koenig, a psychology graduate student at the University of Minnesota in Minneapolis, US, have tried to tease apart how the effects of nature and nurture vary with time. Their study suggests that as adolescents grow into adults, genetic factors become more important in determining how religious a person is, while environmental factors wane.
The study can be found in Journal of Personality (vol 73, p 471)
The title of the paper is:
Genetic and Environmental Influences on Religiousness: Findings for Retrospective and Current Religiousness Ratings
by Laura B. Koenig, Matt McGue, Robert F. Krueger, Thomas J. Bouchard Jr
Abstract Estimates of the degree of genetic and environmental influences on religiousness have varied widely. This variation may, in part, be due to age differences in the samples under study. To investigate the heritability of religiousness and possible age changes in this estimate, both current and retrospective religiousness were assessed by self-report in a sample of adult male twins (169 MZ pairs and 104 DZ pairs, mean age of 33 years). Retrospective reports of religiousness showed little correlation difference between MZ (r=.69) and DZ (r=.59) twins. Reports of current religiousness, however, did show larger MZ (r=.62) than DZ (r=.42) similarity. Biometric analysis of the two religiousness ratings revealed that genetic factors were significantly weaker (12% vs. 44%) and shared environmental factors were significantly stronger (56% vs. 18%) in adolescence compared to adulthood. Analysis of internal and external religiousness subscales of the total score revealed similar results. These findings support the hypothesis that the heritability of religiousness increases from adolescence to adulthood.