In a world in which childbearing is rarely accidental and almost never rewarding economically, birthrates increasingly reflect values choices. And so, by Darwinian process, those who adhere to traditions that preserve and celebrate the ancient injunction to “go forth and multiply” wind up putting more of their genes and ideas into the future than those who don’t. Even if religiously fundamentalist families only have a few more children than secular or religiously moderate counterparts, and they can keep those children holding on to fundamentalist faith and values, the passage of generations will greatly magnify their numbers and influence.