Significance Family members provide the majority of social support for most older adults, but not all individuals have living family. Those without living close kin report higher rates of loneliness and experience elevated risks of chronic diseases and nursing facility placement. How the population of older adults without living family, the kinless population, will change in the coming decades merits consideration. Historical racial differences and recent variation in demographic rates imply unequal burdens of kinlessness for white and black Americans. By projecting the US population using demographic microsimulation, we find increases in lacking kin similar in magnitude to projected increases in other important population health burdens such as diabetes and Alzheimer’s dementia. Increasing kinlessness may represent a growing population health concern.

Abstract Close kin provide many important functions as adults age, affecting health, financial well-being, and happiness. Those without kin report higher rates of loneliness and experience elevated risks of chronic illness and nursing facility placement. Historical racial differences and recent shifts in core demographic rates suggest that white and black older adults in the United States may have unequal availability of close kin and that this gap in availability will widen in the coming decades. Whereas prior work explores the changing composition and size of the childless population or those without spouses, here we consider the kinless population of older adults with no living close family members and how this burden is changing for different race and sex groups. Using demographic microsimulation and the United States Census Bureau’s recent national projections of core demographic rates by race, we examine two definitions of kinlessness: those without a partner or living children, and those without a partner, children, siblings, or parents. Our results suggest dramatic growth in the size of the kinless population as well as increasing racial disparities in percentages kinless. These conclusions are driven by declines in marriage and are robust to different assumptions about the future trajectory of divorce rates or growth in nonmarital partnerships. Our findings draw attention to the potential expansion of older adult loneliness, which is increasingly considered a threat to population health, and the unequal burden kinlessness may place on black Americans.

Older adults without kin are some of the most disadvantaged and isolated members of society (1, 2), because close kin are vital sources of social support that affect social, economic, and physical well-being (3, 4). The availability of kin is repeatedly implicated in studies of healthy aging (5, 6), and lacking kin is among the social factors most positively associated with nursing facility placement and quality of care (7, 8). Loneliness appears to be increasing among older adults (9) and is more strongly associated with early mortality than smoking and excessive alcohol consumption (10). Because kin make up the dominant share of most Americans’ close confidante networks (11), it is no surprise that loneliness is most prevalent among the never married, widowed, and divorced as well as the childless and those without partners (12, 13). Of course, not all close kin are in contact, geographically proximate, emotionally intimate, or willing or able to exchange resources, but the availability of kin is a necessary condition for their provision of such functions (14). For these reasons, it is important to examine the population dynamics of those who lack close kin (15). In the American kinship system (16), demographic events determine the availability of kin, with marriage and fertility producing kin and death and divorce reducing them. The clear links between demographic processes and kinship networks (17, 18) imply that ongoing demographic changes in American society will shift the availability of living kin in the future. However, a continuing revolution in relationship types in older adulthood, particularly the growth of nonmarital partnerships (19, 20), complicates this picture. To best understand changes in the future availability of kin, researchers must consider potential continued increases in nonmarital partnerships.

We draw on theories of cohort succession and demographic metabolism (21) and the methods of computational demography (22, 23) to examine the changing population of kinless individuals in American society over the coming decades. Prior research has examined the increasing percentages and numbers of people who lack specific types of kin, such as the never married (24, 25) or the childless (26, 27), but few studies have put these factors together to consider the subpopulation that simultaneously lacks multiple types of close kin and is at elevated risk of social isolation, loneliness, and hardship (15, 28). The first and second demographic transitions and the gender revolution suggest that the share of people who lack multiple types of close kin is increasing (29, 30). For instance, unions occur less frequently, with delayed marriage and more nonmarriage (31), and historical increases in union dissolution affect cohorts that have recently aged into older adulthood (32, 33). Similarly, cohort childlessness doubled between 1980 and 2000 (34). Putting these factors together, we can expect that more and more Americans will be without close kin in the coming decades. On the other hand, if nonmarital partnerships take on kin-like functions and continue to grow in prevalence (20, 35), they may serve as a buffer against such trends.

Two ongoing demographic changes may further amplify the size of the US kinless population in the future. The first is the rise of “gray divorce,” recent increases in the divorce rate among older adults, which doubled among Americans over 50 y old between 1990 and 2010 (36). Risks of gray divorce are higher among blacks, those with low education and incomes, and for second and subsequent marriages (36). The second set of demographic changes leading to a potential growth in kinlessness is population aging and population growth. In its most recent national projections, the United States Census Bureau estimates that the percentage of Americans age 50 and older will increase from 34.6% in 2015 to 41.5% in 2060 (37). In addition to comprising a larger share of the US population, there will be many more older adults in the future. As the overall population continues to increase, demographers expect that the United States will have 61.8 million more adults ages 50 and above in 2060 than it does today. Recent work finds substantial increases in kinlessness among adults in their 50s and 60s for more recent birth cohorts, which combined with population aging may yield dramatic increases in numbers kinless in the coming decades (15).

The increasing prevalence of cohabitation and dating relationships may offset, to some degree, a potential rise in kinlessness among older adults. Increasingly, relationships formed later in life do not result in marriage (38), and single older adults are now just as likely to form cohabitating as marital unions (39). In 2000, there were more than 1 million cohabiting older adults, who together made up 1.5% of the population older than 50 (20). Other older adults may have a noncoresidential dating partner (40); estimates suggest that 5% of older adults are in such relationships (19). Dating relationships in older adulthood can have a variety of meanings, with some functioning much like marriage and others with less commitment (35). Whether recent increases in these new relationship forms can offset increasing kinlessness depends on how many of these adults also have children and other types of close kin, because those with living children are not kinless. At present, the vast majority (92%) of cohabiting older adults have children (20), as do most (86%) older adults in dating relationships (41). These facts explain why recent work on contemporary kinlessness finds only marginal differences in its population prevalence when nonmarital partnerships are included (15).

Although recent explorations find that white and black Americans of both sexes currently have comparable rates of kinlessness in older adulthood (15), the future burden of kinlessness is unlikely to be equally distributed across race and sex groups, because of differential demographic rates and population aging. Recent research finds large racial differences in the existence of kin of different types using survey data and that these differences are growing in more recent birth cohorts (14). For example, among those aged 45 to 54 in 2011, whites were almost twice as likely to have living spouses as blacks (64% vs. 36%) but slightly less likely to have living children (73% vs. 78%). A portion of these complex patterns is determined by the different ages at which whites and blacks experience kin mortality (14, 42). For instance, by age 60, blacks are twice as likely as whites to have lost a spouse (10.5% vs. 4.9%) and a child (1.0% vs. 0.5%) (42). But, of course, differential fertility also plays a critical role in producing these disparities by altering numbers of children, how many siblings those children have, and age differences between parents and children. There are also differences in nonmarital partnerships by race, with cohabitation and dating more common among blacks than whites (19, 20). Another factor is that whites and blacks are expected to have uneven patterns of population aging. The Census Bureau’s most recent national projections forecast that the share of non-Hispanic whites who are above 50 y old will grow from 41.2% at present to 48.2% by 2060, while the share of non-Hispanic blacks who are older than 50 will grow from 29.0 to 40.1% (37).

Other demographic factors also lead to differences in kin availability between men and women. Women have greater life-course overlap with children and grandchildren because of sex differences in the age at childbearing, age differences between spouses, and greater longevity (43). Women are also less likely to marry and more likely to be widowed or divorced in older age (25, 26). Cohabitation and dating in older adulthood are much less common among women than men, with only 3% of women over 50 cohabiting and 7% dating compared with 6% of men over 50 cohabiting and 27% dating (19, 20). Social gerontologists have examined the different family structures of older adults by sex and what these differences imply for economic well-being, health, and social integration (44, 45). However, it is unknown how sex differences in kin availability will change due to future trends in marriage, partnership, divorce, remarriage, fertility, and mortality.

To understand the combined influence of these demographic trends on kinlessness, we examine how the population of older adults without close kin will change through 2060 and how kinlessness will vary by key population subgroups. We project the size and characteristics of the US population using demographic microsimulation methods that allow us to consider adults ages 50 and above with no living close family members (Approach, Methods, Data, and Measures and SI Appendix). First, we investigate those without a living partner or biological children (kinless 1). In the main text, we focus on partnership between married couples as well as between unmarried parents; in SI Appendix, we consider alternate definitions of partnership. Then, because people without partners and children often leverage sibling relationships for critical kin functions (46), we examine those without a living partner, biological children, parents, or siblings (kinless 2). We compare the largest native-born groups, single-race non-Hispanic white and non-Hispanic black Americans, and examine differences by sex. These groups constituted 84.0% of adults over 50 in the United States in 2014 and are projected to comprise 63.3% of the older adult population in 2060 (37). To maintain simplicity and stay within the constraints imposed by data availability, we do not examine other populations, consider the role of international migration, or examine intergroup marriage. As further justification for these choices, we note that immigration flows to the United States are expected to decline (47), that the stock of international migrants in the United States is under 15% (48), and that the Census Bureau projects that only 1.7% of the US population over 50 y old in 2060 will identify with two or more races (37).

Discussion There is a renewed focus among demographers on the intersections between population processes and kinship, family, and social network structures (55⇓–57). Prior demographic research on kinship has focused on coresidence, intergenerational transfers and exchanges, and the influence of different types of kin resources on the life chances of descendants (58⇓–60). By contrast, counting those without kin and studying the implications of being kinless are neglected undertakings because few population-based surveys ask about noncoresidential kin. Compounding this problem, those without kin are often disadvantaged, and they may be more likely to be in institutionalized care and thereby omitted from the sampling frame of many major surveys. Older adults have lived within dense kin networks for most of human history and the kinless have been a small subpopulation in the modern demographic era (61). However, recent declines in marriage, increases in gray divorce, and fertility decline are leading to larger numbers of older adults with no close family members. Mortality improvements and the increase in new relationship forms among older adults are not large enough to offset these trends. Our findings point to dramatic increases in the numbers of kinless older adults in the United States, whether we consider a broad or a narrow definition of kinlessness. The increases occur for whites and blacks, men and women. By 2060, we expect the population of white and black Americans over 50 y old without a living partner or children to reach as high as 21.1 million, 6.3 million of whom will also lack living siblings or parents, up from our estimates of 14.9 million and 1.8 million, respectively, in 2015. The population of adults who will be over 50 y old in 2060 is already alive, which increases our confidence about probable levels of future kinlessness, barring dramatic changes in projected demographic processes. Our results indicate that growth in numbers without a partner or children is primarily driven by the increasing size of the aging population overall. Although we also find increases in the population percentage that is kinless, this result was most evident among the black population. We find differential growth by race and sex in the share of adults over 50 who are kinless and important differences in the demographic forces driving kinlessness across these groups. There are especially notable increases in kinlessness among blacks, and slightly more for black women than black men. These changes are driven by cohort succession, where increasing numbers of black individuals who never married and never had children are currently aging into older adulthood. Among whites, increases in those without a partner or children are driven by population aging, rather than increases in the population percentage without these two types of close kin. However, when considering increases in those with no living close kin (partner, children, parents, or siblings), we find increases in both the percentages and numbers kinless across race and sex groups. The percentage with no close kin is projected to double by 2060 for whites and more than triple for blacks. Increases in this measure are driven by large increases in having no living kin through the death of one’s siblings, which accounts for more than half of the growth of this type of kinlessness among whites and the vast majority among blacks. This effect is the product of both fertility and mortality forces: Historical fertility declines mean that older adults in the coming decades will increasingly have fewer siblings than previous generations. With fewer siblings, each individual’s risk of all of their siblings having died increases, potentially offsetting gains in older adult survivorship, a feature compounded by decreasing age heterogeneity in sibling sets. Blacks have much larger increases in lacking close kin through the sibling death pathway than whites due to higher mortality. The increasing prevalence of adults raised without siblings in one-child families, which drives population growth among those who never had siblings, is another demographic factor increasing in importance over the projection period. This pathway to kinlessness is more prominent for whites than for blacks. Whether older adults are prepared or unprepared for being without close kin may depend on their pathway to kinlessness. Some pathways to kinlessness may be expected. For instance, those who never marry and never have children know at younger ages that they will not have a partner or children to care for them in older adulthood. They may be able to plan accordingly, either leveraging sibling ties, creating strong kin-like relationships with nonkin, or by relying on institutions for care. Our findings show that this group, those who never married or had children, are driving the largest projected increases in the share of the older kinless population for white men, black men, and black women. These trends are robust to substantial potential growth in new relationship forms. Unexpected kinlessness is more difficult to plan for, and it can come through one of two pathways. The first is the death of kin. Demographers have recently embarked on explorations of this topic and found that it may be an underappreciated dimension of racial inequality (14, 42), but it needs more attention. However, our findings show that a very small percentage of the future population will be kinless because of the death of a partner and children. We find that a second pathway through divorce or widowhood among the childless is the more common entry to unexpected kinlessness. This is the modal route to kinlessness among white women and accounts for a substantial share of kinlessness among other demographic groups as well. Because of large recent increases in divorce at older ages (36), this issue deserves more attention. Even those who lack a living partner or biological children through expected means (e.g., the never married and childless) may still end up experiencing unexpected kinlessness through sibling death. We found that this pathway to unexpected kinlessness accounts for a large percentage of the increasing share of the black population without living close kin, but it is less relevant for whites, which may point to even larger racial disparities in access to social resources in the future. At the same time, if recent increases in white middle-age mortality persist (62), our results may differ such that a larger share of the future white population is kinless through death.

Conclusion The impending increase of kinless older adults is a potentially critical demographic trend for society as a whole, institutions that provide services for older adults, and the kinless themselves. We know that those who lack kin are more likely to be socially isolated, suffer poorer health, and have fewer economic resources. But, of course, not all individuals without kin fit into these categories, and not all those with kin are able to draw on them for social and economic support. A limitation of our focus on the demographic processes driving kinlessness is that we did not examine how geographic proximity, exchange, contact, and emotional closeness might exacerbate or mitigate the effects of a growing kinless population on loneliness and other social issues. Many of those with kin may still be socially isolated, among other factors, because of a lack of these relationship qualities. A related limitation is that we do not focus on step-kin, who may provide an important source of support for older adults (62); future work could consider the role of such individuals. At the same time, while the majority of informal care for older adults is provided by family members (4), some who lack kin may be able to substitute roles traditionally played by partners, children, siblings, or parents with paid help or the camaraderie of friendship. In either case, however, estimates and projections of kinlessness offer a strong starting point to better understand these patterns. We advocate that such topics receive more attention in future work.

Approach, Methods, Data, and Measures To conduct our simulations, we employed the freely available Berkeley Socsim demographic microsimulation model (63⇓–65), which we parameterized with age–sex–state–specific probabilities of individuals experiencing demographic events. We assemble these probabilities from several sources that contain historical and projected, societal-level demographic rates as described in SI Appendix. We provide code for interested researchers to run the Socsim program, obtain our results, and replicate and extend these analyses (https://osf.io/z3suy/?view_only=dac305f99c414e578aceb0eb3aadf5cd). We began with populations of 50,000 white and black individuals drawn from the 1880 Census and simulated the evolution of these groups over time. We run one large simulation for each race group under these parameters, consistent with other microsimulation research (66, 67); at the end of the simulation there are over 290,000 simulated individuals alive and above the age of 50, which yields precise estimates. Microsimulation is the most popular method of assessing how demographic processes affect kinship networks over long periods (22, 68). Demographic microsimulation works by simulating the behaviors of a hypothetical population of individual agents over time, allowing them to marry, divorce, remarry, have children, and die probabilistically at specified age–sex–state–specific rates, where states can be any category such as parity, marital status, or ethnicity. We explicitly model nonmarital fertility and nonmarital partnership defined as relationships between unmarried parents of a child in the main text, with alternate definitions explored in SI Appendix. We use “closed” microsimulation models, in which partnering decisions are constrained by the available population, allowing us to trace the long- and short-term evolution of kinship networks and define relevant kin ties of interest (69).

Acknowledgments We thank Brandon Wagner, Michael Gaddis, Jake Fisher, and Sarah Patterson for manuscript comments, Libby Wagner for graphical assistance, and Carl Mason and the Department of Demography at the University of California, Berkeley for access to Socsim. This work was supported by a Sandell grant from the Center for Retirement Research at Boston College (Grant BC16-S5), the Population Research Institute (Grant R24-HD041025), and the Government of Canada - Canadian Institutes of Health Research (Grant MYB-150262) and Social Sciences and Humanities Research Council (Grants 435-2017-0618 and 890-2016-9000). The HRS (Health and Retirement Study) is sponsored by the National Institute on Aging (Grant NIA U01AG009740) and is conducted by the University of Michigan.

Footnotes Author contributions: A.M.V. and R.M. designed research; A.M.V. and R.M. performed research; A.M.V. analyzed data; and A.M.V. and R.M. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

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