Religious fertility advantages are culturally transmitted, not genetically fixed

Evidence

While the evidence that religious involvement affects fertility rates is strong, no one knows for sure yet what the reasons are for the religious advantage. To complicate things further, part of the explanation may lie not only in religion per se, but in its close cousins, conservatism and fundamentalism. The more conservative and more fundamentalist a community is, the higher the fertility rates, even when we confine the analysis within religious groups. Whatever the exact causes, I think religion’s reproductive advantage, like its effects on cooperation, is best explained as a cultural evolutionary process. This is not to deny that beliefs and attitudes that have effects on reproductive success may have a genetically inherited component. But these values are also, in a very important sense, culturally transmitted. We know this because within the same population, having more or less the same gene pool, there has been dramatic decline of fertility that has followed the decline in religious involvement, sometimes in a matter of just a few decades. — Norenzayan, Ara, Big gods - how religion transformed…, 500

While the evidence that religious involvement affects fertility rates is strong, no one knows for sure yet what the reasons are for the religious advantage. To complicate things further, part of the explanation may lie not only in religion per se, but in its close cousins, conservatism and fundamentalism. The more conservative and more fundamentalist a community is, the higher the fertility rates, even when we confine the analysis within religious groups. Whatever the exact causes, I think religion’s reproductive advantage, like its effects on cooperation, is best explained as a cultural evolutionary process. This is not to deny that beliefs and attitudes that have effects on reproductive success may have a genetically inherited component. But these values are also, in a very important sense, culturally transmitted. We know this because within the same population, having more or less the same gene pool, there has been dramatic decline of fertility that has followed the decline in religious involvement, sometimes in a matter of just a few decades. — Norenzayan, Ara, Big gods - how religion transformed…, 500

Categorization

• XREF: Aligns with the book’s overarching cultural-evolution framing of Big God religions and their competitive success, extending it to demographics.
• QUESTION: The fertility mechanism is flagged as unknown — worth chasing whether the religious advantage operates through Big-God-style cooperative signaling or through conservative family norms unrelated to supernatural belief.
• corroborated: 2 independent passages support this claim — Norenzayan, Ara, Big gods - how religion transformed…, 500