Males' Later-Life Mortality Consequences of Coresidence With Paternal Grandparents: Evidence From Northeast China, 1789-1909

Abstract

This study investigates the effect of early life co-residence with paternal grandparents on male mortality risks in adulthood and older age in Northeast China from 1789 to 1909. Despite growing interest in the influence of grandparents on child outcomes, few studies have examined the impact of co-residence with grandparents in early life on mortality in later life. We find that co-residence with paternal grandmothers in childhood is associated with higher mortality risks for males in adulthood. This may reflect the long-term effects of conflicts between mothers and their mothers-in-law. These results suggest that in extended families, patterns of co-residence in childhood may have long-term consequences for mortality, above and beyond the effects of common environmental and genetic factors, even when effects on childhood mortality are not readily apparent.

Introduction

Family and household context in childhood are of great significance for various aspects of later-life well-being in both developed (Elo et al., 2014; Galobardes et al., 2006; Hayward & Gorman, 2004; Preston et al., 1998) and developing countries (Cunningham et al., 2010; Engle & Breaux, 1998; Evans & Miguel, 2007; Morrell et al., 2003). One contextual feature of obvious interest is co-residence with different types of kin. Studies of effects of childhood co-residence with parents already show that their presence or absence in early life may have long-term consequences: children who lived with a single parent tend to have a higher risk of dying in their later life than children who lived with both parents (Campbell & Lee, 2009; Elo et al., 2014; Hayward & Gorman, 2004). Of course, at least a portion of these effects are indirect, working through adult socioeconomic status and household context, which in turn determine health and mortality outcomes (Elo et al., 2014; Martikainen et al., 2009).

In light of such findings, accumulated evidence on the effects of grandparents’ presence on child survival suggests the possibility that it may also influence mortality in later life. Evidence for the immediate beneficial effects of presence of maternal grandmothers is the most consistent. Studies in countries such as Germany, Japan, India, and Canada have found that the presence of maternal grandmothers is associated with higher chances of child survival, possibly because grandmothers help provide child care (Sear & Mace, 2008). In patrilineal societies such as China’s, children have much more contact with paternal than maternal grandparents. However, there have been few studies of effects on child survival of co-residence with paternal grandparents in patrilineal societies. Among these studies, results are inconsistent (for a summary, see Sear and Mace (2008); Sear and Coall (2011)). Relevant studies of 18^th and 19^th century China suggest that co-residence with a paternal grandfather increased child mortality (Campbell & Lee, 1996, 2002).¹

Understanding the long-term influence of childhood co-residence with grandparents is important. In most historical and some contemporary societies, the norm is for grandparents to live with one or more adult children and their grandchildren. This is certainly true for the site of our study, northeast China, as well as other societies in Asia (Chen et al., 2014; Knodel & Ofstedal, 2002; Logan et al., 1998; Takagi & Silverstein, 2006). Although some studies have argued that multi-generational co-residence is on the decline, there is new evidence that in some developing countries, it is once again increasing (Ruggles & Heggeness, 2008). Even where multi-generational households have become rare, a sizable fraction of the contemporary elderly population may have spent time in one as children.

Our analysis also offers a new perspective on grandparent effects on later life outcomes. As part of the growing attention to multi-generational demographic and stratification processes (Mare, 2011), there is new interest in the implications of co-residence or other interactions with grandparents in childhood on outcomes later in life. However, most work so far has focused on measurement of grandparent influences on socioeconomic attainment (Chan & Boliver, 2013) or determinants of long-term reproductive success as measured by total numbers of descendants two or more generations later (Hawkes, 2004).

We examine the later life mortality consequences for males of childhood co-residence with paternal grandparents in preindustrial northeast China. We not only examine effects of co-residence with grandparents in childhood, but seek to assess the roles of three channels: direct effects on child health that also have long-term consequences, selection effects, and indirect effects. While our exclusive focus on paternal grandparents is due to data limitations described below, it is also the case that in historical China and other historical and contemporary societies characterized by patrilocal marriage, in which wives join their husband’s household, children are much more likely to co-reside with paternal grandparents than with maternal grandparents. The restriction to studying male mortality in adulthood and old age, meanwhile, reflects other limitations of the data described below.

For our analysis, we make use of the China Multigenerational Panel Dataset-Liaoning (CMGPD-LN), which describes approximately 250,000 individuals living in 600 largely rural communities in northeast China from 1789 to 1909. We apply discrete-time event-history analysis (Allison, 1984) to measure male mortality risks in adulthood and older ages according to childhood co-residence with a paternal grandparent, with controls for other features of household context in childhood. In order to control for unobserved characteristics of the household and community that may have influenced the survival of grandparents and grandchildren, we also estimate models with father fixed effects.

This study has at least two distinguishing features. To our knowledge, it is the first study of the mortality consequences in adulthood and old age of childhood co-residence with paternal grandparents for any society in which such co-residence was the norm. Examination of the long-term consequences of presence of a paternal grandparent in childhood is important in societies such as historical China in which married adults co-resided with surviving elderly parents, usually the husband’s. Second, results from this preindustrial and largely agrarian setting may offer insights into the legacy of related processes in contemporary societies, where patriarchal, multi-generational households were also the norm and the population was largely rural when today’s elderly were still children. In such societies, the health and mortality of the elderly now may reflect long-term influences of childhood co-residence with grandparents like those reported here. If data emerge that allow for studies similar to ours for such societies, comparison of the results will yield insight into how specific features of local context condition the relationship between co-residence with paternal grandparents and later life health outcomes.

Background

Co-residence with grandparents and child health

Previous studies suggest a number of pathways by which co-residence with a paternal grandfather may have influenced children’s health. The left half of Figure 1 summarizes these pathways. Co-residence with a grandfather might benefit child health by improving economic well-being or increasing family stability. The former refers to the possibility that in preindustrial societies, grandfathers contributed to the economic well-being of the household by providing labor (Tymicki, 2004, 2009). The latter refers to the possibility that in a patrilocal society like China’s where wives joined their husband’s household at time of marriage, the death of a paternal grandfather might lead to conflicts within the household over inheritance or other issues, and that these conflicts could adversely affect child health (Tymicki, 2004, 2009). Conversely, an adverse effect of co-residence with a grandfather might arise from conflict between junior and senior generations over resources. Children and the elderly all depend on resources generated by working-age adults. In a patriarchal society like China’s, males in the senior generation take precedence over junior males. As a result, children who co-resided with their paternal grandfather may have been allocated fewer resources than those whose paternal grandfather had already passed away (Campbell & Lee, 2004).

Figure 1.

Possible pathways for the effect of childhood co-residence with paternal grandfather on health in later life

Results from previous studies suggest a number of mechanisms by which co-residence with a paternal grandmother may have had an immediate beneficial or adverse effect on infant and child health, depending on the social and cultural context. The left half of Figure 2 summarizes possible pathways by which the presence of a paternal grandmother may influence infant and child health. Many studies emphasize the beneficial direct effects on children of care from a paternal grandmother, or indirect effects arising from help she provides to her daughter-in-law (Beise, 2005; Cunningham et al., 2010; Derosas, 2002; Griffiths et al., 2001; Kemkes-Grottenthaler, 2005; Leonetti et al., 2005). Fewer studies report a negative effect of co-residence with paternal grandmother on infant and child mortality. Explanations for these negative effects focus on conflicts with in-laws (Beise, 2002; Voland & Beise, 2002; Willfuhr, 2009).

Figure 2.

Possible pathways for the effect of childhood co-residence with paternal grandmother on health in later life

Empirical studies on the effect of co-residence with paternal grandparents on mortality risks in childhood yield conflicting results. The review of kin effects on child survival by Sear and Coall (2011) includes a number of studies that considered effects of paternal grandparents. Results vary according to the choice of age range. Common age ranges include 0-2, 0-5, 0-10 and 0-15. Generally speaking, for studies that focus on ages 0-2, age 0-10 or age 0-15, co-residence with a paternal grandfather increases mortality in childhood, and co-residence with a paternal grandmother reduces it (Jamison et al., 2002; Kemkes-Grottenthaler, 2005; Tsuya & Kurosu, 2002, 2004). For those studies that focus on ages 0-5, co-residence with a paternal grandfather reduces mortality, while co-residence with a paternal grandmother has mixed effects (Beise, 2002, 2005; Tymicki, 2004, 2009; Voland & Beise, 2002; Willfuhr, 2009).

Early life influence on adult health

A large body of literature has documented the association between childhood conditions and health in later life. Adversity in early life, whether as the result of competition with co-resident paternal grandfathers over resources, family instability following the death of a paternal grandfather, or in-law conflicts between mothers and co-resident paternal grandmothers, might increase mortality later in life through ‘scarring’ or reduce it through selection, as summarized in the right halves of Figure 1 and Figure 2. On the one hand, adverse conditions in early life that have an immediate effect on mortality risks may permanently impair the health of those who survive, leading to higher death rates later in life (Elo & Preston, 1992; Kuh & Wadsworth, 1993; Mosley & Gray, 1993). This is referred to as a ‘physiological scarring’ effect. On the other hand, various forms of selection effects may lead children who survived a risky childhood to experience lower death rates later in life. Individuals who survived adversity in childhood may have been more robust in the first place (Alter et al., 2001; Elo & Preston, 1992; Preston et al., 1998).

Childhood co-residence with paternal grandparents might also have indirect effects on health and mortality later in life. Such co-residence might directly affect the diet, lifestyle, socioeconomic attainment, or other health-related behaviors of children in adulthood or old age, and thereby influence their health and mortality (Jendrek, 1993; Zeng & Xie, 2014). Furthermore, as suggested in the right halves of Figures 1 and 2, resource competition or family stability associated with childhood co-residence with grandparents could affect socioeconomic status in adulthood, and thus affect their health and mortality.

Much of the discussion of possible mechanisms of the long-term influences of childhood context focuses on the potential role of experiences during critical periods of development. According to the critical period model, shocks which occur when specific organ systems are developing may impair health in later life because they have long-term effects on the functioning of those systems (Ben-Shlomo & Kuh, 2002). Conditions in utero have received particular attention because different organs develop at specific times during pregnancy (Hayward & Gorman, 2004). Indeed, this is the basis of the original ‘fetal origins hypothesis’ (Barker, 1992). Conditions in the first years of life are also important because infancy and early childhood are crucial periods of growth and development.

Hypotheses

Based on our reading of this literature, we specify a set of hypotheses corresponding to contrasting scenarios for mechanisms by which co-residence with grandparents may have affected health in later life. We consider paternal grandfathers and paternal grandmothers separately, with one pair of hypotheses (H1ab) for effects of paternal grandfathers, and another pair (H2ab) for paternal grandmothers. We also consider a hypothesis (H3) to account for the possibility that any observed benefit of co-residence in later life might be the production of selection processes in childhood.

• Co-residence with a paternal grandfather in childhood increases mortality later in life because discrimination in favor of senior males in the allocation of household resources led to physiological ‘scarring’ of junior males. (H1a)

• Childhood co-residence with a paternal grandfather lowers mortality later in life because the labor they contributed improved household economic standing and their presence promoted family stability (Tymicki, 2004, 2009). (H1b)

• Childhood co-residence with a paternal grandmother increases mortality later in life because of physiological ‘scarring’ caused by in-law conflicts between paternal grandmothers and mothers in childhood. (H2a)

• Childhood co-residence with a paternal grandmother lowers mortality later in life because of the assistance that they provided assistance to the mother. (H2b)

• Childhood co-residence with paternal grandfathers or grandmothers lowers mortality later in life because the higher infant and child mortality produced by resource competition with them (Campbell & Lee, 1996, 2002) selected out the least healthy children, and/or left surviving children immune to the diseases responsible for the higher mortality. (H3)

Data

We make use of data from China Multi-Generational Panel Dataset, Liaoning (CMGPD-LN), 1749-1909 (Lee & Campbell, 2011). The CMGPD-LN consists of 1,513,357 triennial observations of 266,091 individuals who lived in rural northeast China between the late 18^th and early 20^th centuries. It is organized by household, kin group, village, administrative district, and region. The data provides extensive details on household relationship, age, name(s) and name changes, occupation, marriage, emigration, geographic location, socioeconomic status as well as information on fertility and mortality. Importantly, the CMGPD-LN also includes a constructed outcome variable specifying whether or not an individual dies in the next three years. This is specifically intended for use as a dependent variable in a discrete-time event-history analysis of mortality. Because the data are publicly available via ICPSR and already well-documented (Dong et al., 2015; Lee & Campbell, 1997; Lee et al., 2010), discussion here focuses on features directly relevant to the analysis.²

The data has three features especially relevant to the needs of this analysis. First, in contrast with most contemporary longitudinal surveys of the elderly, the CMGPD-LN records early life and adult circumstances prospectively, rather than relying on retrospective reports by respondents. The records in the CMGPD-LN not only follow males across their life course, but also link them to their parents and paternal grandparents. At every point in time, details on household context are available. This addresses a major difficulty in studying the determinants of health over the life course in a multi-generational perspective: the scarcity of prospective data not only follows individuals from childhood to old age, but also follows families and households over multiple generations. Second, the suitability of the CMGPD-LN for analysis of mortality has already been established. It has been used in several published studies of mortality (Campbell & Lee, 1996, 2002, 2004) and at least two studies of early life influences on adult and old age mortality (Campbell & Lee, 2009; Dong & Lee, 2014). Properties of the data relevant to the study of mortality are known and limitations have been identified and accounted for. Third, the population was closed. Entries into and exits from the population were extremely rare and when they did occur, they were annotated. In contrast with most other historical population databases, after people left their origin village for another one, they were still recorded. We do not need to worry about differential loss to follow-up among individuals according to their mortality risks (Lee & Campbell, 1997).

The CMGPD-LN also has limitations relevant to this analysis. First, records of many children who died in early childhood were missing, so we are unable to reliably calculate mortality rates in infancy or early childhood as a proxy for disease exposure in early life (Forsdahl, 2002; Leon & Smith, 2000). Along these lines, direct measures of exposure to disease that are central to theories about influences of early life conditions on health in later life (Ben-Shlomo & Kuh, 2002) are not available. Second, the CMGPD-LN only allows study of childhood contextual influences on later life mortality for males because at present it is not possible to follow a woman from her natal household to her husband’s household after she marries. The problem is that the available data do not allow for records of married women to be linked back to their records as daughters in their natal households. Although the ideal study would examine both men and women, we are not able to conduct such a study and we avoid generalizing from our results for males.

Third, our variables for age at loss of grandparent or other kin are based on the age at which they were last recorded in a register as alive, rather than a recorded age at death. Records in the CMGPD-LN specify that a death has occurred in the last three years, but do not provide the exact date of death. If a death was recorded in a register that is missing, we only know the year in which they were last recorded as alive in the available data. To have a consistent measure, we rely on age in sui at the last live appearance of a grandparent. This will tend to underestimate the age at death of grandparents.

We apply a variety of restrictions to the observations in the dataset to account for other limitations of the CMGPD-LN. We include data from 1789-1909 because registers before 1789 did not distinguish separate residential households within larger administrative units.³ We restrict the data to observations of individuals who were between 1 and 75 sui and for whom another observation is available three years later. The latter restriction ensures that we only consider time intervals during which a death in the next three years could have been recorded in a surviving register. We also exclude individuals who we are unable to link to parents or grandparents, and those cases for which values for mother’s age at the child’s birth are implausible.⁴ Our final sample consists of 406,335 observations describing the life courses of 85,677 males.

Methods

We apply discrete-time event-history analysis (Allison, 1984) to examine the roles of the channels through which co-residence with paternal grandparents in childhood may influence later life mortality risks. Discrete-time event-history analysis via logistic regression is an appropriate method in light of the structure of the data. Previous studies of mortality in the CMGPD-LN have all used discrete-time event history analysis because, as noted earlier, the data only specify the three year interval in which a death occurred, rather than the actual date of death (Campbell & Lee, 1996, 2001, 2002, 2004). Discrete-time event-history analysis is specifically designed for such data, in which only the interval in which an event occurred is known, but the actual date is not (Allison, 1984). While complementary log-log regression should yield coefficients that are directly comparable to ones produced by proportional hazards models (Long, 1997), our previous experiments with both forms of regressions indicate that the results are nearly identical.

To control for unobserved community or family characteristics that simultaneously influence grandparent survival and grandchild mortality in childhood or later in life, in addition to estimating models with controls for observed characteristics of the household, we also estimate models that include fixed effects for fathers. In such models, we can rule out the possibility that an observed association is the product of the influence of unobserved characteristics of the community and household on the health of the grandparent and the grandchildren.

To adjudicate among our hypotheses, we run separate analyses for the effect of co-residence with paternal grandfather in early life on mortality in childhood, adulthood and old age. If scarring is important (H1a and H2a), childhood co-residence with a grandparent should increase mortality in childhood, adulthood and old age. If selection is important, childhood co-residence with a grandfather should raise child mortality but lower adult and old age mortality (H3). If labor contributions and family stability play a role (H1b), childhood co-residence with a paternal grandfather should lower child mortality as well as mortality in later life. If co-residence with a paternal grandmother is beneficial because of the assistance that she provided to the mother (H2b), it should be associated with lower mortality risks later in life.

We estimate logistic regressions with and without fixed effects of grandfather for three separate age groups: boys aged 1-15 sui, adult males aged 16-55 sui and elderly males aged 56-75 sui. These ranges are intended to correspond roughly to 0-15, 15-55 and 55-75 Western years of age. Within each age group, Model 1 includes the indicators of grandparents’ co-residence in the year of birth, and controls for age, region, year, and other controls such as household context and socioeconomic status. To account for unobserved characteristics of the household that affect mortality risks, Model 2 adds a fixed effects of fathers, and eliminates variables that will be the same among brothers, such as time-invariant characteristics of their parents (Allison & Christakis, 2006; Hoffman & Duncan, 1988). Results for effects of co-residence with the paternal grandfather reflect comparisons between brothers according to whether their grandfather was still alive when they were children.

Our first set of analyses focuses on the association between mortality risks and co-residence with grandparents in or around the year of birth. Here co-residence with grandparents in the year of birth serves as a proxy for whether the child co-resided with them in infancy and early childhood. Because of the way that the CMGPD-LN is structured, the variable for co-residence with grandparents in year of birth will actually reflect co-residence with that grandparent from birth up to the time of the next triennial household register. Typically, this will be sometime in infancy or early childhood.

In the rural society covered by the CMGPD-LN, adult children almost always co-resided with the father’s parents. Thus if a paternal grandparent was alive, a child almost always lived with him or her. An adverse effect of co-residence with a grandparent around time of birth would imply that grandchildren competed with the grandfather for household resources (H1a) or suffered from in-law conflicts between the grandmother and the mother (H2a), while a beneficial effect would imply that the grandfather improved household environments (H1b), or the grandmother assisted parents with care (H2b), or selection effects (H3).

To assess the influence of duration of co-residence with grandparents, we make use of a ‘critical period model’ that recognizes the potential influence of exposure during specific time periods in childhood. We conduct a parallel analysis to look at whether the influence of co-residence on child mortality varies by the age of the child, and whether duration of childhood co-residence conditions mortality outcomes in adulthood, and old age. Each set consists of two models, one with and one without fixed effects of fathers. These examine the immediate effects on mortality of co-residence at specific ages in childhood, and the longer-term effects of the duration of co-residence with the grandparent. In the historical Chinese context, since adult couples co-reside with the father’s parents, grandchildren almost always live with their surviving paternal grandparents. In this context, a child’s age at the time their grandparent died doubles as a measure of the duration of their period of co-residence with that grandparent. Since most theories about critical periods emphasize the importance of conditions in utero or infancy, we expect co-residence with grandparents at early ages to have been most important, and continued co-residence at later ages to have had only minor additional effects.

We also examine whether the effect of co-residence with a grandparent around time of birth was conditioned by the presence or absence of a parent of the same sex. We hypothesize that any adverse effect of co-residence with a grandmother (H2a) would be weaker for a child who lost their mother, because there was no possibility for conflict between her and her mother-in-law. Any beneficial effects of co-residence with a grandmother (H2b) might be magnified because the grandmother might substitute for her in providing care, or ensuring that another family member would provide care. For this, we include variables indicating parental survival status and longevity, and interaction terms between grandparents’ and parents’ survival status around the time of birth. Similarly, we expect that for children who lost their father around the time they were born, the adverse effect of a grandfather would be weaker (H1a) or the beneficial effect of a grandfather would be stronger (H1b) because a grandfather might partially substitute for the father in supplying labor for the household.

Measures

The key right-hand side variables in the current analysis are co-residence with paternal grandfather and grandmother at time of birth. We first create two dummy variables to indicate the co-residence of paternal grandfather and grandmother around the time of the child’s birth. We treat “survival of grandparents” and “co-residence with grandparents” as interchangeable because if paternal grandparents were alive, children almost always co-resided with them (Lee & Campbell, 1997). To construct this measure, we compare each individual’s calculated year of birth to the register year in which their grandmother or grandfather was last recorded as alive.⁵ If the year of last observation for the grandparent is equal to or greater than the child’s calculated year of birth, the grandparent is considered to be co-resident at the time of birth.⁶

We use the child’s age when their grandparent was last recorded as alive as a proxy for their age at the time of their grandparent’s death, and the duration of their childhood co-residence with that grandparent. For the analysis of mortality of children under age 16 sui, we test the immediate effects on mortality of co-residence at specific ages in childhood by interacting current age group with whether or not the paternal grandfather and paternal grandmother are currently alive. For the analyses of adult and old age mortality, we divide individuals into three categories according to their age when their paternal grandfather or grandmother was last recorded: 1 to 5 sui, 6 to 10 sui, or 11 sui and onwards, in order to test the longer-term effects of the duration of co-residence with the grandparent. The reference category includes men whose paternal grandfather or grandmother died before they were born.

Basic controls include age, year, and region. As noted earlier, ages were recorded in sui in original registers. In the analysis, age in sui is entered as a quadratic polynomial. Region is entered as dummies, indicating north, central, south central, or south Liaoning. Mortality levels vary dramatically across these regions. Mortality was lowest in south and south central Liaoning, higher in north Liaoning, and highest in the central region, which was also the most densely settled. We control for year because Campbell and Lee (2004) and other studies suggest a trend of declining infant and child mortality in the population during the 19^th century.

We also include controls for features of household context that previous studies have shown to be associated with mortality in historical China (Campbell & Lee, 2009) and which may plausibly be correlated with the presence of grandparents. We capture an individual’s childhood socioeconomic status by creating dummy variables indicating whether their father held a salaried official position or had a diminutive name. We capture their status in adulthood in old age by creating dummy variables for whether the individual held a position. Having a salaried official position is a sign of being local elite while having a diminutive name in historical China was generally associated with low status.⁷

Controls for household context include maternal birth age, paternal birth order, number of present brothers, birth interval, presence of parents, and grandparents’ longevity. Maternal birth age, short preceding birth interval, paternal birth order, number of present brothers and presence of parents in childhood are found to significantly affect both child and adult mortality (Campbell & Lee, 2009). Maternal age at birth is measured using two indicators. One identifies individuals who were born when their mother was 20 sui or younger, and the other identifies individuals who were born when their mother was 35 sui or older. Number of brothers is calculated directly from the data. A short preceding birth interval is defined as a maternal birth interval from zero to two years. Dummy variables are included to indicate whether the individual’s father or mother was currently alive. We also include an indicator of grandparents’ exceptional longevity as an alternate approach to account for correlated mortality risks as a result of common genes or environment. Grandparents’ longevity is measured using two dummy variables that indicate whether a grandfather or a grandmother lived to more than 60 sui, in order to capture those cases where grandparents lived to especially old ages.

We also control for marital status as a potential intervening variable in adult and old age mortality. Previous studies also show that married males have lower mortality than unmarried males in a large number of countries (Hu & Goldman, 1990). A previous exploration of CMGPD-LN shows that parental survival influenced male marriage chances: men whose parents were still alive were more likely to marry (Chen et al., 2014). Family socioeconomic status also influence marriage chances, with men from higher status families were more likely to marry early. Marital status may therefore have been a proxy for otherwise unobserved aspects of socio-economic status in historical Northeast China. Marital status is recoded as a dummy variable indicating whether an individual was currently married or not.

Table 1 summarizes the variables in the analysis divided by age group. For our key independent variables, the grandfather was alive at the time of the subject’s birth for around 38 percent of the observations, while the grandmother was alive for around 56 percent of the observations. These percentages are very similar across all three age groups. This mitigates concerns of sample selection bias stemming from the possibility that co-residence with grandparents at time of birth might affect the chances of survival to adulthood or old age.

Table 1.

Means of the Variables Included in the Analysis by Age Group

Variable	Mean/Proportion
	Total	1-15 sui	16-55 sui	56-75 sui
Co-residence with Grandparent at birth
Grandfather alive at birth (Alive=1)	0.383	0.389	0.381	0.377
Grandmother alive at birth (Alive=1)	0.562	0.554	0.566	0.562
Socioeconomic status
Married	0.442	0.026	0.651	0.611
Had position	0.016	–	0.022	0.035
Father had diminutive name	0.034	0.051	–	–
Father had diminutive name in childhood	0.069	–	0.072	0.085
Father had position	0.028	0.035	–	–
Father had position in childhood	0.037	–	0.037	0.031
Household context
Grandfather alive (Alive=1)	0.128	0.302	–	–
Grandmother alive (Alive=1)	0.208	0.454	–	–
Father alive (Alive=1)	0.557	0.883	0.448	–
Mother alive (Alive=1)	0.635	0.935	0.547	–
Father alive at birth (Alive=1)	0.951	0.949	0.952	0.953
Mother alive at birth (Alive=1)	0.989	0.987	0.990	0.992
Grandfather lived longer than 60	0.497	0.503	0.498	0.467
Grandmother lived longer than 60	0.605	0.589	0.616	0.598
Father lived longer than 60	0.464	0.389	0.496	0.535
Mother lived longer than 60	0.514	0.414	0.555	0.627
Short preceding birth interval	0.106	0.100	0.108	0.116
Birth order among siblings	2.168	2.116	2.195	2.181
No. of survive brothers	1.127	1.004	1.245	0.788
Maternal age (Ref= Mother=21-35 sui at birth)
Mother <= 20 sui at birth	0.114	0.121	0.111	0.112
Mother >= 36 sui at birth	0.210	0.212	0.211	0.197
Demographic variables
Year	1857.385	1857.581	1856.216	1864.807
Region (Ref=Northern Liaoning)
Central Liaoning	0.292	0.271	0.303	30.030
Southern Liaoning	0.199	0.215	0.193	18.190
Southern Central Northern Liaoning	0.124	0.139	0.116	11.410
No. of death	0.044	0.035	0.034	0.153
N	406,335	134,165	238,175	33,995

Descriptive Results

Descriptive results are consistent with H1b or H2b: individuals who co-resided with a paternal grandfather at time of birth have higher overall survival chances in adulthood and old age, while co-residence with a grandmother at time of birth is beneficial in adulthood, not old age. Figure 3 presents the Kaplan-Meier smoothed hazard estimates in adulthood and old age for individuals who survived to at least age 16 sui, according to whether they co-resided with a grandfather or grandmother at birth. The mortality hazards for people who co-resided with a grandfather at birth are lower than for those who did not, particularly during adulthood. Until age 60, the mortality hazards for people who co-resided with a grandmother at birth are slightly lower than for those who did not. At that point, there is a cross-over, and the mortality hazard for those who co-resided with a grandmother at birth becomes higher than for those who did not. A log rank test shows strong, significant differences between the hazards by grandfathers’ survival status at birth (χ²(1) = 26.69, p = .000). Overall, there are fewer deaths among persons whose grandfathers were alive at birth than those whose grandfathers were not. The effect of grandmothers’ survival status at birth is weakly significant (χ²(1) = 2.88, p = .090).

Figure 3.

Kaplan-Meier Hazard Estimates by Survival Status of Grandparents at Birth

Descriptive results for the effects of co-residence with a grandparent around time of birth if the parent of the same sex passed away are inconclusive. Figures 4 and 5 present the relevant results. There are no significant differences between the hazard curves by co-residence with a grandfather (χ²(1) = 0.35, p = .553) or grandmother (χ²(1) = 0.22, p = .636) at birth, as indicated by log rank tests. However, among people whose parents were still alive at their time of birth, there are fewer deaths among people who co-resided with a grandfather at birth than among those whose grandfathers died before birth (χ²(1) = 22.74, p = .000). While visual inspection of the Kaplan-Meier smoothed hazard estimates in Figure 4 and 5 may suggest larger differences according to the survival status of a grandparent when men lost a parent of the same sex around time of birth, these differences are not statistically significant.

Figure 4.

Kaplan-Meier Hazard Estimates by Survival Status of Grandfather at Birth, Conditional on Survival Status of Parents

Figure 5.

Kaplan-Meier Hazard Estimates by Survival Status of Grandmother at Birth, Conditional on Survival Status of Parents

Event History Analysis

Presence of Paternal Grandparents at Time of Birth

To assess whether selection processes existed could have produced a pattern in which co-residence increased child mortality but reduced mortality later in life (H3), we begin with an assessment of effects of co-residence on child mortality. Analyzing an earlier, smaller version of the CMGPD-LN, Campbell and Lee (1996, 2004) reported adverse effects of presence of a grandfather, which they attributed to resource competition with a dependent patriarch. They examined overall effects of grandparent co-residence on mortality of children between ages 2 and 15, and did not distinguish effects by age group. Results in Model 1 of Table 2 confirm the adverse effect of co-residence with paternal grandfather on child mortality. However, after the introduction of fixed effects for father in model 2, associations are no longer statistically significant. The apparent effect of co-residence with a grandfather in Model 1 may be an artifact of association of child mortality with unobserved community or household characteristics that had an opposite effect on grandfather’s mortality. No significant effects are found for grandmothers in any model.

Table 2.

Logistic Regression of Male Child (1-15 sui) Mortality on Family Context, Liaoning, 1749-1909

	Logistic regression	Logistic regression with fixed effect of father	Logistic regression	Logistic regression with fixed effect of father
	Model 1	Model 2	Model 3	Model 4
Co-residence with Grandparent at birth
Grandfather alive at birth (Alive=1)	0.0781* (0.0380)	0.0443 (0.104)
Grandmother alive at birth (Alive=1)	0.0576 (0.0408)	−0.138 (0.0966)
Age * Grandfather alive
1-5 sui			0.161** (0.0476)	0.0631 (0.106)
6-10 sui			−0.133† (0.0778)	−0.0132 (0.103)
11+ sui			−0.171† (0.0979)	−0.177 (0.129)
Age * Grandmother alive
1-5 sui			0.107* (0.0501)	0.0270 (0.0991)
6-10 sui			−0.0316 (0.0746)	−0.0681 (0.0984)
11+ sui			0.00359 (0.0863)	−0.138 (0.115)
N	134,165	17,652	134,165	17,652
Group		3,331		3,331

Standard errors in parentheses.

^†p < 0.1

^*p < 0.05

^**p < 0.01

^***p < 0.001.

To save space, coefficients for controls for parent, grandparent, and household characteristics, circumstances of birth, age, year, and region are not shown. See Appendix Table A1 for the full results.

Presence of a paternal grandmother at time of birth has clear adverse effects on adult male mortality. Models 1 and 2 in Table 3 present relevant results from the event-history analyses of adult mortality.⁸ In Model 1 without fixed effects, co-residence with a grandfather or a grandmother alive at birth does not have a significant effect. However, the patterns change once unobserved characteristics of the family are accounted for in Model 2 by the introduction of fixed effects. Consistent with H2a, men whose grandmother was still alive when they were born have odds of dying 25.1 percent higher than brothers born after that grandmother had passed away (e^0.224 = 1.251). In other words, among brothers who differed according to whether or not their paternal grandmother was still alive when they were born, the ones whose grandmothers were still alive had higher death rates in adulthood. An association between adult female mortality and community characteristics may have been suppressing the effect of co-residence of grandmother in Model 1. Meanwhile, no significant effects are found for grandfathers after the introduction of father fixed effects. For old age, we did not find any significant effect of co-residence with grandfathers or grandmothers at the time of birth on mortality.

Table 3.

Logistic Regression of Adult Male (16-55 sui) Mortality on Current and Childhood Family Context, Liaoning, 1749-1909

	Logistic regression	Logistic regression with fixed effect of father	Logistic regression	Logistic regression with fixed effect of father
	Model 1	Model 2	Model 3	Model 4
Co-residence with Grandparent at birth
Grandfather alive at birth (Alive=1)	−0.0514† (0.0303)	0.0703 (0.0810)
Grandmother alive at birth (Alive=1)	−0.00698 (0.0316)	0.224** (0.0725)
Age when grandfather last observed alive (Ref=Grandfather not alive at birth)
1-5 sui			−0.0333 (0.0396)	0.0188 (0.0860)
6-10 sui			−0.0135 (0.0457)	0.201† (0.106)
>11 sui			−0.0830* (0.0399)	−0.113 (0.124)
Age when grandmother last observed alive (Ref=Grandmother not alive at birth)
1-5 sui			0.00779 (0.0398)	0.199* (0.0804)
6-10 sui			0.0180 (0.0429)	0.231* (0.0897)
>11 sui			−0.0317 (0.0375)	0.294** (0.0940)
N	238,175	66,295	238,175	66,295
Group		6,641		6,641

Standard errors in parentheses

^†p < 0.1

^*p < 0.05

^**p < 0.01

^***p < 0.001.

To save space, coefficients for controls for parent, grandparent, and household characteristics, circumstances of birth, age, year, and region are not shown. See Appendix Table A2 for the full results.

Co-Residence with Grandparents Later in Childhood

We explore whether the immediate or long-term effect of co-residence with grandparents in childhood varies by the duration of co-residence. The results are shown as models 3 and 4 in Tables 2, 3, and 4, for childhood, adulthood, and old age, respectively. When we break down the effect by the age of the child, we find an adverse effect of co-residence with grandfathers and grandmothers for children who are not yet 5. However, the magnitudes of these effects become smaller after the introduction of father fixed effects, and they are no longer statistically significant. Comparison with the results for Model 2 in the same table confirms that co-residence with grandparents has no effect in childhood once comparison is made between siblings differed according to age at the loss of their grandfather.

Table 4.

Logistic Regression of Elderly Male (56-75 sui) Mortality on Current and Childhood Family Context, Liaoning, 1749-1909

	Logistic regression	Logistic regression with fixed effect of father	Logistic regression	Logistic regression with fixed effect of father
	Model 1	Model 2	Model 3	Model 4
Co-residence with Grandparent at birth
Grandfather alive at birth (Alive=1)	−0.00335 (0.0412)	0.0749 (0.171)
Grandmother alive at birth (Alive=1)	−0.0129 (0.0437)	−0.155 (0.148)
Age when grandfather last observed alive (Ref=Grandfather not alive at birth)
1-5 sui			−0.0158 (0.0540)	0.128 (0.181)
6-10 sui			−0.0428 (0.0628)	−0.0170 (0.223)
> 11 sui			0.0500 (0.0534)	0.194 (0.266)
Age when grandmother last observed alive (Ref=Grandmother not alive at birth)
1-5 sui			0.0425 (0.0547)	−0.170 (0.160)
6-10 sui			−0.0522 (0.0589)	−0.102 (0.189)
> 11 sui			−0.0453 (0.0516)	−0.220 (0.197)
N	33,995	13,397	33,995	13,397
Group		3,310		3,310

Standard errors in parentheses

^†p < 0.1

^*p < 0.05

^**p < 0.01

^***p < 0.001.

To save space, coefficients for controls for parent, grandparent, and household characteristics, circumstances of birth, age, year, and region are not shown. See Appendix Table A3 for the full results.

Co-residence with a paternal grandmother later in childhood has long-term adverse effects on adult mortality (H2a). According to Model 4 in Table 3, when a fixed effect of father is included, co-residence with a grandmother has adverse effects on adult mortality regardless of the duration of co-residence. The odds of dying are 22 percent (e^0.199 = 1.220), 26 percent (e^0.231 = 1.260), and 34.2 percent (e^0.294 = 1.342) higher than brothers whose grandmothers were dead when they were born when co-residing with a grandmother at 1-5 sui, 6-10 sui, and 11 sui and onwards, respectively. These results indicate that the longer a man co-resides with his grandmother in childhood, the higher mortality risk he has in adulthood. This result reflects comparisons between brothers and is net of intergenerational correlations in longevity. Results for the effects of co-residence with grandfather are inconclusive. According to the results in Model 3 of Table 3, men whose grandfather was last seen alive when they were aged 11 sui or older have a lower mortality risk. In Model 4, which includes father fixed effects, this beneficial effect disappears. Long-term effects of co-residence with grandparents in childhood are not apparent in old age, as shown in Table 4.

We present the results of robustness checks for adult mortality in Table A5 of the online appendix. We first include household context variables indicating the presence of father and mother around the time of the individual’s birth. We also experiment with inclusion of variables indicating parents’ longevity, measured by whether a father or a mother lived longer than 60 years old, to capture cases where parents lived to exceptionally advanced ages. The results are consistent with those in Table 3.

Interaction between Loss of Parent around Time of Birth and Presence of Grandparents

For men who experienced loss of their mother around time of birth, co-residence with a grandmother had a strong beneficial effect on adult mortality. By contrast, co-residence with both a grandmother and a mother at the time of birth has an adverse effect on adult mortality. These patterns are consistent with the in-law conflicts hypothesis (H2a). As is shown in the fixed effects model in Table 5, for an adult aged 16 to 55 sui, compared with brothers whose mother was alive around their time of birth but whose grandmother was no longer alive, men who lost their mother around their time of birth but had a co-residing paternal grandmother had 37.8 (1 − e^{(−0.941+0.232+0.234)} = 0.622, p=0.053) percent lower odds of dying in the next 3 years. Adult males whose mothers and grandmothers were both alive at the time of birth have a 26.4 (e^0.234 = 1.264) percent higher odds of dying in the next three years than men whose mother was alive but not their grandmother. The model includes controls for birth order, so these results are not an artifact of the fact that boys who lost their mother are by definition last-born. No significant results are found for co-residence with grandfathers.

Table 5.

Social Support from Grandparents in Childhood and Long-term Mortality Risks

	Logistic regression		Logistic regression with fixed effect of father
	16-55 sui	56-75 sui	16-55 sui	56-75 sui
Co-residence with Grandparent at birth
Grandfather alive at birth (Alive=1)	−0.0614* (0.0306)	−0.00707 (0.0416)	0.0625 (0.0812)	0.0870 (0.173)
Grandmother alive at birth (Alive=1)	−0.0177 (0.0318)	−0.0130 (0.0439)	0.234** (0.0728)	−0.156 (0.149)
Loss of father at birth (Loss=1)	−0.0187 (0.0592)	−0.0364 (0.0811)	0.0338 (0.138)	0.148 (0.287)
Loss of mother at birth (Loss=1)	−0.160 (0.149)	0.0258 (0.216)	0.232 (0.275)	0.612 (0.862)
Grandfather alive at birth ╳ Loss of father at birth	0.0496 (0.144)	0.0416 (0.201)	0.415 (0.382)	−0.409 (0.688)
Grandmother alive at birth ╳ Loss of mother at birth	0.0424 (0.234)	0.0727 (0.350)	−0.941† (0.485)	−0.306 (1.218)
N	238,175	33,995	66,295	13,397
Group			6,641	3,310

Standard errors in parentheses

^†p < 0.1

^*p < 0.05

^**p < 0.01

^***p < 0.001.

To save space, coefficients for controls for parent, grandparent, and household characteristics, circumstances of birth, age, year, and region are not shown. See Appendix Table A4 for the full results.

The results suggest that even though there may be an overall adverse effect of co-residence with a paternal grandmother, in the specific case where a mother passed away right after a boy was born, the presence of a paternal grandmother was beneficial. Either they substituted for the mother in providing care for the child, or they were able to advocate for the child in household negotiations over the allocation of resources. Moreover, the fact that mortality was highest for men whose mother and grandmother were both alive around the time of their birth, and lower if only their mother or only their grandmother was alive, is consistent with the suggestion in H2a that elevated mortality associated with the presence of a grandmother was at least partly due to conflict between the mother and her mother-in-law.

Conclusions

Childhood co-residence has consequences for mortality at later ages. Co-residence with a paternal grandmother in childhood raises mortality risks in adulthood (H2a), and this adverse effect increases with the duration of co-residence. All these findings are robust to the inclusion of controls for family and household characteristics in childhood and adulthood, including socioeconomic status and early household context, as well as common effects of unobserved characteristics within a household. These results are consistent with the ‘scarring’ channel proposed above (H2a). Results were not consistent with a selection process (H3), beneficial effects of presence of a paternal grandfather associated with their labor contributions (H1b) or beneficial effects of a paternal grandmother associated with assistance they provided to mothers (H2b). While co-residence with a grandmother in childhood has an adverse effect on mortality in adulthood, boys who lived with either their mother or grandmother but not both around the time of birth had lower mortality in adulthood, which is consistent with the suggestion in H2a that conflict between a mother and her mother-in-law could produce harmful effects. No significant effects on mortality are found for co-residence with paternal grandfathers in childhood. Effects of co-residence with paternal grandmothers on later life mortality vary according to the duration of co-residence, consistent with the idea that there were ‘critical periods.’

This study contributes to the literature on the long-term consequences of early life context in several ways. It considers a previously understudied topic, the long-term influence of co-residence with grandparents early in life. While grandparent effects on child wellbeing are already the subject of a very large literature, and grandparent effects on socioeconomic attainment are the subject of a rapidly growing literature, there are few studies of the effects of childhood co-residence with grandparents on health in adulthood and old age.

Our study is also distinctive in that it makes use of data from a preindustrial, primarily rural society where mortality was high and the household was the most important unit of social organization. While the data have limitations that affect our ability to generalize, most notably due to the inability to follow women across the life course and measure the effects of co-residence in childhood on their elderly mortality, the results nevertheless demonstrate the potential importance of a mechanism that should be studied in other settings where better data may become available.

An important implication of these results is that in extended families in patriarchal societies, patterns of co-residence in childhood may have long-term consequences for health and mortality, net of common environmental and genetic factors. Significance of the effect of co-residence with grandmothers after introduction of fixed effects tells us the association found is not a product of unobserved common household features. A more general implication of these results is that they confirm that studies which measure grandparent effects on socioeconomic and health outcomes later in life need to consider co-residence in childhood or other exposure as an intervening variable (Song & Mare, 2017), at least in societies where multi-generational households are common.

Our findings may also have special implications for understanding health and mortality among the elderly in the many non-Western societies where co-residence with grandparents was still common when today’s elderly were still young. While societies characterized by patrilocal residence and an ideal of multi-generational co-residence such as India and China are the most obvious examples, some form of co-residence with grandparents was also common elsewhere in Asia and Africa. The social context under our examination is a preindustrial rural society where mortality was high and the household was the most important unit of social organization, which is comparable to the environment in which the elderly in many contemporary developing countries spent their childhood. More generally, this suggests that contemporary mortality among the elderly in developing countries may reflect the legacy of co-residence in childhood many decades ago. To the extent that mortality is reflective of underlying health, the implication is that contemporary differentials in health among the elderly may reflect differences in their experience of co-residence in childhood. Obviously the social and cultural context of co-residence in other settings would differ, and we hope that as more data become available, comparison between settings will help illuminate specific mechanisms driving these associations.