I have very clear memories of attending Sunday school as a kid, and spending most of that time thinking my teachers were putting me on. Do I lack something that other people have? Are there genes that predispose people to belief or non-belief?
There certainly are such genes involved in predisposition to religiousness. There is non-trivial heritability toward religious zeal. By heritability I mean the proportion of popuation level variation in a trait than can be explained by variation in the genes. This is a subtle point: just because a constellation of genes may affect the propensity toward religiosity, that does not imply that there were selection for religious belief. Rather, it maybe that religion is a phenomenon which is a byproduct of normal human psychological processes. And just as humans exhibit variation on a whole host of psychological characteristics, so any trait which emerges as a side effect of said traits shall also exhibit variation.
Imagine if you will a value which measures receptivity toward religious teachings and beliefs:
Now, imagine the following prediction equation:
Religious receptivity = Social intelligenceX(deviation from population norm) + Agency detectionX(deviation from population norm) Analytic intelligenceX(deviation from population norm)….
A whole host of psychological tendencies, all heritable, may result in a propensity toward religious belief, or, a lack of such propensity. This model can explain why levels of avowed belief vary between societies: quantitative traits exhibit a high level of environmental variance. In other words, in addition to the genetic factors environmental context matters. Some people may simply be unable to sincerely accept theism, while others may need a “helping hand” from social pressure. Similarly, there maybe individuals who simpy are compelled to believe by an inner compass which will brook no rational argument.