Stephen Mihm, an associate professor of history at the University of Georgia, is a contributor to Bloomberg Opinion. Read more opinion SHARE THIS ARTICLE Share Tweet Post Email

Photographer: John C. H. Grabill/Getty Images Photographer: John C. H. Grabill/Getty Images

A recent Pew Research Center report delivered the sobering news that millennials -- a group the public seems to believe consists entirely of adults living in their parents' basements -- are in fact having a hard time starting their own households. Despite improvements in the economy, adults aged 18 to 34 are living with their parents in greater numbers: 26 percent today as opposed to 24 percent back in 2010.

This has prompted yet another round of hand-wringing about the failures of this particular demographic group. But the larger sweep of history should nudge us to reconsider whether there's anything wrong with millennials. In fact, if there's anything wrong here, it's our society's expectations that the "normal" thing for adults to do is to break away from their parents as quickly as possible. For most of the nation's history, multigenerational living arrangements were the norm, not the exception.

It's true that in the mid-20th century, the nuclear family was typical. While a small fraction of the population lived in multigenerational households, most adults maintained their distance from aging parents. The housing of postwar suburbs embodied this ideal, and mid-century experts on family life preached the virtues of a sharp, clean break between generations.

In the process, the idea of adult children living with their parents -- or vice versa -- came to be seen as something pathological. This consensus proved so powerful that historians of the family bought into it. Many scholars published research in the 1960s and 1970s purporting to show that Americans had always lived in nuclear families, with generations keeping each other at other at arm's length.

But recent research has revealed a far more complicated picture -- one that should be reassuring to millennials and their parents alike. Historical demographers such as Steven Ruggles have used a database maintained by the Historical Census Project at the Minnesota Population Center to call into question many of our assumptions about what constitutes a "normal" family in the past and present.

Ruggles, for instance, has challenged the idea that different generations actively sought to live apart. Yes, he observed, multigenerational families may not have been ubiquitous, but there are some obvious explanations for this fact. Take, for example, the lifespan of the average American prior to the 20th century. As Ruggles has written, "many people did not live with their parents simply because their parents were dead."

That said, Ruggles found that a staggering number of those who made it past 50 did, in fact, live with their children. In 1850, for example, some 80 percent of white Americans aged 50 to 54 lived with their children. Given that a not-insignificant number of the elderly never had kids, and therefore couldn't live in a multigenerational family, it appears that the practice was close to universal. In other words, if you were an adult and one or more of your parents were alive, they would likely be living with you.

The skeptic, of course, would look at these numbers and point out that what was going on here was precisely the opposite of what's happening today: Infirm, sick, elderly parents must have been moving in with their children. The younger generation, then, was the one doing the supporting, not the other way around.

But that's actually not the case. Thanks to a quirk in the 1880 census which asked about the physical health of the household members, it's possible to determine whether or not there's a correlation between parental health and multigenerational families. That reveals a clear trend: Sick parents were actually less likely to end up living with their children. The typical multigenerational family, in other words, consisted of healthy older parents with grown children. Not coincidentally, these aging parents were typically listed as the heads of their households -- not the other way around.

Some of this intriguing finding can be attributed to the fact that many Americans still lived on farms, and adult children waiting to inherit property would reasonably stick around until their parents died. The multigenerational family, in other words, could be taken to be a peculiar artifact of a long-gone agricultural economy. If so, it might have limited relevance for today's millennials, few of whom are living in the parental basement while they wait to inherit the farm.

But the history is far more complicated -- and interesting. Census takers broke down the occupations of multigenerational families. When Ruggles analyzed this data (and removed all farm families) he found that people who fell into the top quarter of income distribution -- professionals such as engineers, professors, doctors, lawyers, stockbrokers and corporate managers-- were the most likely to maintain multigenerational families. Families stuck on the lowest rungs of the occupational ladder, by contrast, were the least likely to do so.

The upshot? In the late 19th century, adult children were more likely to live with their parents if they came from families that were college-educated, wealthy and possessed of significant resources, whether in the form of agricultural land or intellectual and social capital. They stuck close to home because it gave them access to far more resources than they could command on their own.

It was only in the 20th century that this pattern started to fall apart. Over time, the correlation between multigenerational living arrangements and wealth started to reverse itself. By 1990, the process was complete: Multigenerational families had become more common among the poor than among the wealthy. Much of this was undoubtedly driven by developments peculiar to the 20th century, such as postwar suburbia and changing notions of what constitutes an ideal family.

Whether the results of the Pew study portend any genuine return to an older model of family life is an open question: Two percentage points is hardly the stuff of radical social change. It's also worth emphasizing, as Zara Kessler recently did, that the shift seems to have affected all millennials, regardless of educational attainment.

But if this turns into a trend, a bit less hysteria and a deeper appreciation of the history of multigenerational households might be helpful. Today's millennials may be embracing family arrangements that were once the norm, not the exception. The helicopter parents, the adult children who prove reluctant to leave home -- perhaps we've been here already.

This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

To contact the author on this story:

Stephen Mihm at smihm1@bloomberg.net

To contact the editor on this story:

Tracy Walsh at twalsh67@bloomberg.net