Breaking Up is Hard to Do, Unless Everyone Else is Doing it Too: Social Network Effects on Divorce in a Longitudinal Sample Forthcoming in Social Forces

Divorce represents the dissolution of a social tie, but it is also possible that attitudes about divorce flow across social ties. To explore how social networks influence divorce and vice versa, we exploit a longitudinal data set from the long-running Framingham Heart Study. The results suggest that divorce can spread between friends. Clusters of divorces extend to two degrees of separation in the network. Popular people are less likely to get divorced, divorcees have denser social networks, and they are much more likely to remarry other divorcees. Interestingly, the presence of children does not influence the likelihood of divorce, but each child reduces the susceptibility to being influenced by peers who get divorced. Overall, the results suggest that attending to the health of one’s friends’ marriages may serve to support and enhance the durability of one’s own relationship, and that, from a policy perspective, divorce should be understood as a collective phenomenon that extends beyond those directly affected. Structure and Spread of Divorce 3 According to the National Center for Health Statistics (Bramlett & Mosher, 2001), about 43% of marriages will end in divorce within the first 15 years of marriage, and, as of 2007, the annual incidence of divorce stands at 36 per 1,000 people (National Vital Statistics Reports, 2007). Moreover, remarriage, while common, tends to be even less successful than first marriage, resulting in higher rates of divorce with each successive trip down the aisle (Krieder & Fields 2002). These numbers matter because the individual health and welfare consequences for those who get divorced and the influence of divorce on subsequent child development can be significant. But they also raise questions about whether there is an “epidemic” of divorce and, if so, whether there is a role of social contagion in this “epidemic.” Anecdotal examples of miniature “epidemics” among celebrity networks abound, including the announced divorces of Al Gore and his daughter around the same time. But does such a process play out more generally? A great deal of work in sociological theory addresses the determinants of marriage and the bases of divorce. Some of this work posits marriage as a form of social exchange, whereby internal benefits (sex) and costs (time) are calculated and weighed relative to external costs (money) and benefits (social approval) (Becker, 1991). From this perspective, externally imposed stressors, such as financial strain, for example, might potentiate the risk of divorce (Conger et al., 1990; Sayer & Bianchi, 2000). Under this model, the risk of divorce rises when the rewards of staying in a marriage diminish relative to the costs, or when one or both partners perceive better alternatives to exist (Amato et al., 2007). Employment prospects, as well as the degree and type of outside activities, certainly affect prospects for the availability of suitable alternative partners (South and Lloyd, 1995). Evaluations of the intrinsic costs and benefits of relationships, however, take place relative to one’s social reference group; thus, norms regarding fairness, loyalty, or other aspects of relationships would likely influence interpretations of the value of any given relationship and the permissibility of divorce. Moreover, social reference groups are relevant to the prospect of finding other partners (Frisco & Williams, 2003; Lennon & Rosenfield, 1994). These Structure and Spread of Divorce 4 assessments are, of course, influenced by gendered norms and expectations concerning the institution of marriage itself (Kalmijn & Poortman, 2006; Thompson & Walker, 1989). From this relatively individual-centered, cost-benefit-assessment perspective, those who experience high costs and low rewards are more likely to divorce (Nock, 1995; Sanchez & Gager, 2000). However, such individual or dyadic approaches often fail to explore the ways in which a couple’s social situation and community network can also affect the status of their marriage and their prospects for marital dissolution. Here, we examine the effect of divorce among one’s peers, and even among others farther away in the social network, on one’s own divorce risk. One possibility is that people who get divorced promote divorce in others by demonstrating that it is personally beneficial (or at least tolerable) or by providing support that allows an individual to contemplate and endure a rupture in their primary relationship. People in an unhappy relationship may be happier either on their own, embedded in a wider network of friends, or with a different partner. Another possibility is that people who get divorced inhibit divorce in others by demonstrating that it may be more personally costly than expected. People who watch another’s painful process of divorce may decide that their own unhappiness is worth bearing in order to avoid the cost of breaking up on themselves or their children. If the inhibitory effect of divorce is weaker than the promotion effect, then divorce might spread through a social network via a process of social contagion (involving a variety of mechanisms) from person to person to person. Hence, the question remains whether contact with others reinforces a decision by unhappy spouses to stay in suboptimal relationships, or whether deeply engaged friends instead potentiate fissure in such relationships, in part by providing more effective forms of support. More broadly, little is known about how inter-personal connections affect divorce, and prior literature has not explored the wider possibility of person-to-person-to-person effects on divorce, although the logic of such investigation seems clear. If one person’s divorce affects another’s likelihood of initiating marital disruption, why wouldn’t such effects diffuse through society in a more widespread manner? Structure and Spread of Divorce 5 The association between the divorce status of individuals connected to each other, and the clustering of divorce within a social network, could be attributed to at least three processes: 1) influence or contagion, whereby one person’s divorce promotes or inhibits divorce in others; 2) homophily, whereby people with the same divorce status choose one another as friends and become connected (i.e., the tendency of like to attract like) (McPherson et al. 2001); or 3) confounding, whereby connected individuals jointly experience contemporaneous exposures (such as an economic downturn or co-residence in a wealthy neighborhood) that influence the likelihood of divorce. To distinguish among these effects requires repeated measures of divorce (Carrington et al., 2005), longitudinal information about network ties, and information about the nature or direction of the ties (e.g., who nominated whom as a friend) (Fowler & Christakis, 2008b; Christakis & Fowler 2013). There are two issues here, two distinct ways that social networks might affect divorce risk. First, the structure of the network in which one is embedded can itself affect risk of divorce. For example, the greater the transitivity of the network around a married couple (the more their friends are friends with each other), the lower their risk of divorce might be (similar, for example, to the effect Bearman and Moody found with respect to suicide risk in adolescent girls (2004)). Or, possibly, the more peripheral a couple is in the social network, the greater their risk of divorce might be. Second, regardless of structure, processes of social contagion could operate within the network. Here, the issue is what kinds of attitudes and behaviors are evinced by one’s network neighbors, and what effects these might have. So, the greater the incidence of divorce among one’s friends, the higher the likelihood one would follow suit. Prior work on how the architecture of social networks affects divorce risk is limited. Similarly, prior work on how attitudes towards divorce might diffuse through social networks is also scarce. Structure and Spread of Divorce 6 Network Structure and Divorce The existing literature on divorce offers some evidence regarding the impact of social support networks on the likelihood of marital rupture. Some older work suggests that spouses who share the same friends are less likely to get divorced than those who do not (Ackerman, 1963). Other research from a nationally representative sample indicates that weaker network ties to one’s spouse increase chances for marital infidelity, a factor that predisposes partners to divorce (Treas & Giesen, 2000). Yet such relationships are neither simple nor straightforward in nature. As Booth et al. (1991, 222) write: “simple embeddedness in the social fabric of society may not be sufficient to explain why some marriages endure and others break up.” To examine more subtle aspects of the influence of networks on marriage, additional work has explored a more nuanced characterization of social network support, examining different types of relationships. Bryant & Conger (1999) studied three types of influence to examine whether network support helps encourage a couple to stay together or instead drives them apart. First, they studied outside support for the relationship from friends and family to see whether approval for the relationship provides an important predictor of relationship success, as some earlier work suggested (Johnson & Milardo, 1984). Second, they examined whether shared social network contacts enhanced marital satisfaction, including whether liking each other’s friends can improve marital happiness. Last, they investigated whether personal support within the relationship improved chances for marital success. An important aspect of this last component relates to a sense of reciprocal equality in the relationship, or whether one person feels he or she gives more than the other within the context of the marriage. Interestingly, only outside support from friends and family predicted marital success in the time period examined. The authors suggest an endogenous mechanism is at work among those who achieve success in relationships: “The greater the feelings of satisfaction, stability and commitment that partners have for their relationships, the greater the evidence for supportive extramarital relationships. In turn, the more supportive network members are, the greater are feelings of Structure and Spread of Divorce 7 satisfaction, stability and commitment that partners have for their marital relationships. (448)” This provides some insight into the reasons why popularity, as defined by increased social exposure, approval, and support, may decrease the risk of divorce. If a spouse is popular, they may be more able to solicit and receive the kind of supportive extramarital friendships that strengthen their marital bonds than those who have less social resources to depend on in times of marital trouble. Only one longitudinal panel study (Booth et al., 1991) has addressed the question of whether a greater number of social ties, and more frequent interaction among them, decreases the likelihood of divorce. The authors of this study defined communicative integration as the degree to which individuals remain embedded in a large social network and normative integration as a lack of divorce among one’s reference group members. They found a small negative effect of communicative integration on divorce, but only for those who had been married less than seven years. Importantly, they found that normative integration reduced the likelihood of divorce, regardless of how long people had been married: “When one’s reference group includes siblings or friends who have divorced, the individual is more likely to divorce.” (221). Part of the reason for this may be that when friends become divorced, more convenient and familiar options for new partnerships open up to those in the same network. This suggests the hypothesis that divorced people might be more likely to marry one another. Finally, despite the tremendous attention paid to the influence of divorce on children, relatively less interest has been dedicated to the impact of children on the probability of divorce. Waite & Lillard (1991) found that firstborn children enhance marital stability until the child reaches school age. Additional children improve the prospects for marital stability only while they remain very young. Having children prior to marriage, or having older children, portends poorly for marital endurance. In sum, these authors find that children only provide a marginal improvement in the likelihood of a marriage surviving twenty years. It may be that the financial and time stresses associated with having children place a heavy burden on married couples, but they are too busy to attend to anything but the immediate needs of their children until they are Structure and Spread of Divorce 8 self-sufficient. Once children are older, the parents may feel there is less need to remain together “for the sake of the children” if the central relationship itself has become strained to the point of breaking. Heaton (1990), using a regression analysis on a current population sample, reported the stabilizing influence of up to three children on a marriage, noting that five or more children increased risk of divorce. This similarly suggests that while some people may stay together because of children, too many can push couples over the tipping point where cooperation, even for the sake of children, may no longer seem possible. Commensurate with the Waite & Lillard (1991) findings, Heaton (1990) also indicated that as children get older, the risk of divorce rises until the youngest child left home. Network Contagion and Divorce Existing work in person-to-person transmission has focused particularly those related to parent-to-child intergenerational transfer of divorce risk. One common hypothesis is that parents who divorce are significantly more likely to produce progeny who also show an increased propensity to experience ruptured marriages; this tendency becomes exacerbated when both partners have parents who experienced divorce themselves (Bumpass et al., 1991; Feng et al., 1999; Keith & Finlay, 1988; Kulka & Winesgarten, 1979; Mueller & Pope, 1977.). In particular, daughters of divorced parents are more likely to divorce (Feng et al., 1999); one large study found that the risk of divorce in the first five years of marriage increased 70% among daughters of divorced parents (Bumpass et al, 1991). This risk may transfer differentially to daughters because such women display a stronger commitment to employment and plan to have fewer children, reducing their expected economic dependence on men (Goldscheider & Waite, 1991). While wives’ employment can ease financial stress in a marriage, it simultaneously potentiates conflict over household chores and childrearing, making marriages less enjoyable for both partners (Hochschild, 1989). Wives’ financial independence makes divorce more economically feasible for such women Structure and Spread of Divorce 9 Demographic patterns play an important mediating role in the association between parental and child divorce (for an excellent review, see Amato, 1996). For example, age of marriage strongly influences prospects for success; young marriages are less likely to survive, and children of divorce tend to marry younger (Glenn & Kramer, 1987; Keith & Finlay, 1988). Another factor which rivals age in inducing marital stability appears to lie in holding similar religious beliefs; in general, intrafaith unions suffer divorce less frequently than interfaith ones (Lehrer & Chiswick, 1993). Children of divorce also seem to be more likely to cohabit prior to marriage, which some have argued is associated with increased divorce rates (Bumpass et al., 1989, Thornton, 1991; but see Elwert, 2007). In addition, compared with children from intact families, children of divorce attain less educational status, make less income, and have lowerlevel jobs, all of which combine to enhance the risk of divorce (Conger et al., 1990; Mueller & Cooper, 1986). In addition to these demographic factors, some work suggests that specific behaviors play a key role in potentiating the risk of divorce. For example, children may learn destructive traits, like jealousy or distrust, from their parents, and import such problematic tendencies into their own relationships, or they may fail to learn important interpersonal skills, like the ability to communicate clearly or compromise effectively (Amato 1996; Wallerstein & Blakeslee, 1989). Teachman’s (2002) work shows how the intergenerational transfer of divorce may result from the inheritance of personality traits, which lead, in turn, to lower levels of social functioning and higher risk of divorce. Parental investment in social network support may also provide a model to children as well, such that more popular parents offer more and better opportunities for potential mates and other forms of social support to their children as well. All these factors thus affect parent-child transmission of divorce risk. Moreover, marriage, like friendship, may sort according to degree of such functioning, with higher functioning individuals being both more likely to find and keep suitable mates and also more able to find social support outside marriage in other friendships (should the relationship prove challenging). Structure and Spread of Divorce 10 Hence, most of the work exploring the relationship between social networks and divorce has concentrated on person-to-person effects, and has not even tried to explore person-to-person to –person effects, or the extent to which a divorce by one couple might affect those separated by two degrees. But earlier work on outcomes such as happiness highlight the possibility that complex social processes such as divorce might be affected by social network processes (Fowler & Christakis, 2008a). Limitations of Previous Work Distinct from the foregoing, the literature has not addressed how – conversely – divorce can affect networks. As Bryant & Conger conclude in their own study: “Most of the existing work only presents evidence of networks influencing relationships, rather than relationships influencing networks (448).” That is, almost none of the literature has examined the reciprocal impact of divorce on the surrounding social network. This is curious, since the act of divorce directly affects the structure of a network by removing an existing tie, and since divorce in one person might also affect the risk of divorce among his or her friends and other social contacts. We explore here the possibility that divorce can affect social networks, just as social networks can affect divorce, precisely because a shift in one person’s marital status may influence the marital status of others in that network as occurs, for example, when two divorced people remarry one another. Note also that these extant studies focus almost exclusively on parent-to-child transmission of risk factors for divorce, ignoring the potentially important impact of the peer-topeer influence we explore here. In addition, outside of intergenerational transmission, little work has explored the relative importance of type of relationship on social influence in divorce. Can friends who live far away influence their geographically remote friends’ prospects for divorce? What about coworkers who a person might see every day, but with whom they might not feel especially close? Will such individuals in our network affect prospects for divorce more or less than a sibling or parent? Structure and Spread of Divorce 11 Finally, previous studies have been relatively less able to address questions of causality because of a lack of longitudinal data. Here, we use a 32-year longitudinal study that contains information about marital and other network ties. We hypothesize that structural features of the network in which people are embedded will affect their divorce risk, that divorce can diffuse through the social network from person to person, and that divorce can in turn modify social network structure. We use a variety of analytic approaches to partially address thorny problems of causal inference in this setting.