If any value is deeply evolutionarily familiar, it is reproductive success. If any value is truly unnatural, if there is one thing that humans (and all other species in nature) are decisively not designed for, it is voluntary childlessness. All living organisms in nature, including humans, are evolutionarily designed to reproduce. Reproductive success is the ultimate end of all biological existence.
For every woman who's ever wondered about the path not taken, Fenton and Steinke mine—with tremendous humor and insight—the mixed blessing of unexpected second chances.