Below I made a reference to the heritability of religiosity. In a chat with Christer Chris that the heritability for religiosity was 0.5, and he was surprised at the result. I decided to double-check, and here is the latest paper:
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.
In Bouchard's "twins raised apart" studies he found about a 0.5 heritability. In any case, remember what heritability is: The proportion of population level variance attributable to genetic variance. Why does environmental variance become so much less important once you leave adolescence? Take a guess.... Psalms 137:9 Happy shall he be, that taketh and dasheth thy little ones against the stones.
