Human beings imagine and encounter the future most intensely through our own progeny, our flesh and blood. The Constitution speaks of “our posterity” for a reason: We are a nation of immigrants, but when people think about the undiscovered America of the future, its strongest claim on them is one their own descendants make.

If those descendants exist. But for many native-born Americans there are fewer of them — fewer children and, as birthrates drop and marrying age rises, still-fewer grandchildren or none at all. Which means that when they look ahead into their country’s future, white baby boomers especially see less to recognize immediately as their own.

This alienation is heightened when the descendants they do have seem to be faring worse than they did — as in those white working-class communities where opioid addiction, worklessness and family breakdown have advanced apace. The combination of small families and social disarray feeds a grim vision of the future, in which after you’ve passed, your few kids and fewer grandkids will be beset, isolated and alone.

This sense of dread, in turn, bleeds easily into ethno-racial anxiety when the benefits of that imagined future seem to belong increasingly to people who seem culturally alien, to inheritors who aren’t your natural heirs. For this reason mass immigration, the technocratic solution to the economic problems created by post-familialism — fewer workers supporting more retirees — is a double-edged sword: It replaces the missing workers but exacerbates intergenerational alienation, because it heightens anxieties about inheritance and loss.