An article in Evolutionary Psychological Science looks at the “secularization hypothesis,” the assumption that modernity would be accompanied with the gradual dying out of religion. That is proving not to be the case, with many researchers trying to figure out why.
The authors of this study sought a biological reason. They found a strong correlation between “religiosity” and family size. Conversely, they found a very strong correlation between the degree of “secularism” and small family size. That is to say, atheists tend to have very few children.