…with almost wholly separate life histories:
Image from Brad Wilcox, from CDC data.
The thing to note about this is that there is no reason to believe that these two groups will necessarily converge, or even that one will shrink indefinitely relative to the other. The two modes represent two different causal processes; women who do not marry and have children early and women who do marry and have children late will likely have children who resemble them, for both cultural and biological reasons.
Will individual women and their families move from one equilibrium to another, through cultural pressure or legal changes or technology that facilitates one type of behavior more or less? Of course. And there’s still the chance that we’re entering a period of much more rapid behavioral change among younger cohorts of adult women, with marked declines in marriage rates among 25-35 year olds- although as Philip Cohen has often noted, the percentage of women who will ever marry has declined less than the percentage of women who are married at any given young age, since women marry later than they did before.
But from the perspective of children’s experiences, there are now two ways of growing up in America, both about equally common: with an older, married, usually fairly well-educated and well-off mother, or with a younger, unmarried, usually less educated and less affluent mother. The temptation for both public policy and for the culture at large is to pretend that one of these is the dominant one, and the other marginal. This temptation works in both directions; calling the half of kids who grow up in married homes uniquely, unusually privileged is as inaccurate as treating the half of kids who grow up in unmarried homes as a borderline group in dire circumstances.
American public policy has had relative success in the last two decades in moving young, low income mothers into the low-wage labor market and off of cash public assistance. Meanwhile, in broad strokes many well-educated, married women find an agreeable compromise between feminist principles and a preference for working part time or leaving the labor force and then returning. For now, the American economy is wealthy enough to support both tracks of motherhood.
And, for now, we shouldn’t forget that both ways of growing up are pretty normal, and, if we don’t torch the economy or burn up the limited amount of social capital our communities still have left, both kinds of kids will probably grow up just fine.