A Genetically Informed Study of the Intergenerational Transmission of Marital Instability

Intergenerational Transmission of Divorce in Sweden, 1920-2015

Many studies demonstrate an intergenerational transmission of divorce with a focus primarily on more recent decades; however, the extent to which this relationship is deeply rooted or has changed over time remains unclear. Explanations, including sociodemographic and interpersonal factors, have been offered as links between parental divorce and the stability of offspring's marriage. We use individual-level longitudinal data from the Scanian Economic-Demographic Database to estimate the intergenerational transmission of divorce among first marriages in Sweden over the period 1920-2015. Our investigation focuses on the correlation between parental divorce and offspring's divorce during the transition from a low- to a high-divorce regime. Findings reveal surprising stability in the transmission despite fundamental societal change over the years. Notably, the risk of divorce is highest when either the wife or both spouses have experienced parental divorce. Moreover, the transmission of divorce across time appears to be stronger and more stable for women than for men. These results suggest the intergenerational transmission of divorce is part of the divorce transition and highlight the role of women's independence in this intricate but not yet fully understood process.

The Intergenerational Transmission of Family Dissolution: How it Varies by Social Class Origin and Birth Cohort

Children from separated parents are more likely to also experience the dissolution of their own union. For many children, parental separation thus is an adverse life course event that follows them into adulthood. We examine whether parents' social class mitigates this adversity and weakens the intergenerational transmission of family dissolution for children from advantaged class origins. This is the case if separated parents with more resources are able to offer better living conditions to their children and keep them longer in education, reducing children's incentives for early home-leaving, early cohabitation and early childbearing-three life course choices that increase the risk of later family dissolution. We analyse the existence of such a compensatory class advantage for three birth cohorts in the UK. Based on 38,000 life histories from two panel surveys (BHPS, UKLHS), we find a strong link between parents' family dissolution and offspring's family dissolution, and a reversal in the effect of parents' class on children's risk of family dissolution over the three birth cohorts of the Silent Generation (1925-45), Baby Boomers (1946-64) and Generation X (1965-79). However, there is no evidence that the intergenerational transmission of union dissolution is mitigated by a compensatory class effect for offspring from more advantaged class origins. Regardless of class origin, parents' union dissolution is associated with a much larger risk of union dissolution among their offspring.

Understanding the early life mediators behind the intergenerational transmission of partnership dissolution

Whilst research has demonstrated an intergenerational transmission of partnership dissolution, there is limited evidence as to the early life course pathways through which these associations operate, and whether these differ by gender. Many studies have not considered prospective data from early childhood, thus potentially neglecting the importance of the early childhood period in explaining this intergenerational transmission. Given that serial partnering has become increasingly commonplace it is important research considers those who experience multiple partnership dissolution. This paper examines, using data from the 1970 British Birth Cohort Study, the early life mediators underpinning the association between parental separation and the number of offspring partnership dissolutions. Among both men and women there is a significant unadjusted relationship between parental separation and the experience of multiple partnership dissolutions in adulthood. These associations were reduced once parental confounders and childhood mediators are included. Formal mediation analyses demonstrated that early life mediators accounted for more of the association in men than women. Mediators included childhood living standards, and for men child cognition and child behaviour, and for women maternal mental wellbeing. Parental separation and many early life mediators were related to the likelihood of multiple partnership dissolutions through age at first partnership.

The mediating pathways between parental separation in childhood and offspring hypertension at midlife

Social life course determinants of adult hypertension are relatively unknown. This paper examines how parental separation before age 10 relates to hypertension at age 46. Adjusting for parental confounders and considering the role of adult mediators, we aim to quantify unexplored mediating pathways in childhood using prospectively collected data. Data from the 1970 British Birth Cohort Study are utilised. Hypertension is measured by health care professionals at age 46. Potential mediating pathways in childhood include body mass index (BMI), systolic and diastolic blood pressure, illness, disability, family socioeconomic status (SES) and cognitive and developmental indicators at age 10. Additionally, we explore to what extent childhood mediators operate through adult mediators, including health behaviours, family SES, BMI and mental wellbeing. We also test for effect modification of the relationship between parental separation and hypertension by gender. Nested logistic regression models test the significance of potential mediating variables. Formal mediation analysis utilising Karlson Holm and Breen (KHB) method quantify the direct and indirect effect of parental separation on offspring hypertension at midlife. There was an association between parental separation and hypertension in mid-life in women but not men. For women, family SES and cognitive and behavioural development indicators at age 10 partly mediate the relationship between parental separation and hypertension at age 46. When adult mediators including, health behaviours, family SES, BMI and mental wellbeing are included, the associations between the childhood predictors and adult hypertension are attenuated, suggesting that these childhood mediators in turn may work through adult mediators to affect the risk of hypertension in midlife. We found family SES in childhood, cognitive and behaviour development indicators at age 10, including disruptive behaviour, coordination and locus of control in childhood, to be important mediators of the relationship between parental separation and midlife hypertension suggesting that intervening in childhood may modify adult hypertension risk.

Twins Living Apart: Behavioral Insights/Twin Study Reviews: Managing Monochorionic-Diamniotic Twin Pregnancies; Paternity Testing in Multiple Pregnancies; Twin Research on Resilience; Trisomies in Twin Pregnancies/Human Interest: Reunited Brazilian Twins; Website for Twins with Disabled Co-Twins; Twins Separated in Secret of the Nile Series; Mengele: Unmasking the Angel of Death; Twins Helping Others

A brief review of research findings regarding twins living apart is presented. This review is followed by a look into the lives of a pair of monozygotic male twins who have lived in different continents for many years, but who stay closely connected. The reasons behind their decision and its impact on their behavioral resemblance and social relationship quality are examined. The next section summarizes recent studies that address the management of monochorionic-diamniotic twin pregnancies, paternity testing in multiple pregnancies, trisomies in twin pregnancies and the roots of resilience. The final portion of this article presents human-interest stories involving reunited Brazilian twins, a new resource for twins with disabled co-twins, twins separated in the Secret of the Nile television series, a new book about Dr Josef Mengele and his horrific twin experiments conducted at the Auschwitz-Birkenau concentration camp, and a pair of twins dedicated to helping others.

Investigating the association between family connectedness and self-control in adolescence in a genetically sensitive design

Family connectedness is key for the development of self-control in early and middle childhood. But is family connectedness still important during the transitional phase of adolescence, when adolescents demand more independence from their parents and rely more on their peers? The aim of the present study was to investigate the association between family connectedness and self-control, and whether it still holds in adolescence using a genetically sensitive design. Data were used from a large sample of twins aged 14 (N = 11,260) and aged 16 (N = 8175), all enrolled in the Netherlands Twin Register. We applied bivariate twin models and monozygotic twin difference models to investigate the association between family connectedness and self-control and to unravel to what extent genetic and environmental factors explain this association. The results showed that more family connectedness is significantly related to better self-control in adolescence, albeit with a small effect size. Twin analyses revealed that this association was mainly explained by common genetic factors and that the effects of environmental factors were small. The current findings confirm the role of family connectedness in adolescent self-control. Importantly, however, the results demonstrate that phenomena we see within families seem the product of parent and children sharing the same genes rather than being exclusively attributable to environmental processes.

The Role of Emergence in Genetically Informed Relationships Research: A Methodological Analysis

This paper provides a critical analysis of genetically informed research on relationships, with an emphasis on relationships among unrelated individuals (e.g., spouses). To date, research in this area has used traditional behavioral genetic frameworks to either partition the variance in relationship-related outcomes into genetic and environmental components, or to examine gene-environment interplay between relationship factors and other outcomes. However, this conventional approach is at odds with the long-standing understanding from the field of relationship science that both partners' characteristics matter when predicting shared outcomes-that is, outcomes that are emergent. We examine briefly the philosophical concept of emergence, and discuss ways to model dyadic outcomes in genetically informed relationships research. We also review the related topic of social genetic effects, which refer to the influence of a social partner's genotype on a proband's phenotype. A genetically informed dyadic perspective has potentially important consequences for our understanding of the pathways from genotype→shared or individual-level phenotypes, and more fully recognizes the complexity of how genetic and social/environmental factors come together to influence human behavior.

Genetics, the Rearing Environment, and the Intergenerational Transmission of Divorce: A Swedish National Adoption Study

We used classical and extended adoption designs in Swedish registries to disentangle genetic and rearing-environment influences on the intergenerational transmission of divorce. In classical adoption analyses, adoptees ( n = 19,715) resembled their biological parents, rather than their adoptive parents, in their history of divorce. In extended adoption analyses, offspring ( n = 82,698) resembled their not-lived-with fathers and their lived-with mothers. There was stronger resemblance to lived-with mothers, providing indirect evidence of rearing-environment influences on the intergenerational transmission of divorce. The heritability of divorce assessed across generations was 0.13. We attempted to replicate our findings using within-generation data from adoptive and biological siblings ( ns = 8,523-53,097). Adoptees resembled their biological, not adoptive, siblings in their history of divorce. Thus, there was consistent evidence that genetic factors contributed to the intergenerational transmission of divorce but weaker evidence for a rearing-environment effect of divorce. Within-generation data from siblings supported these conclusions.

The Intergenerational Transmission of Union Instability in Early Adulthood

Research on the intergenerational transmission of divorce should be expanded to incorporate disrupted nonmarital cohabitations. The current study (1) examined the transmission of union instability from parents to offspring using Waves I and IV of Add Health, (2) replaced the binary variables (divorced versus non-divorced) typically used in this literature with count variables (number of disrupted unions), (3) relied on independent sources for data on parents' and offspring's union disruptions to minimize same-source bias, (4) assessed the mediating role of 11 theoretically derived variables (many not previously considered in this literature), and (5) incorporated information on discord in intact parental unions. Parent and offspring union disruptions were positively linked, with each parental disruption associated with a 16% increase in the number of offspring disruptions, net of controls. The mediators collectively accounted for 44% of the estimated intergenerational effect. Parent discord in intact unions also was associated with more offspring disruptions.

Methods for Handling Missing Secondary Respondent Data

Secondary respondent data are underutilized because researchers avoid using these data in the presence of substantial missing data. We reviewed, critically evaluated, and tested potential solutions to this problem. Five strategies of dealing with missing partner data are reviewed: complete case analysis, inverse probability weighting, correction with a Heckman selection model, maximum likelihood estimation, and multiple imputation. Two approaches were used to evaluate the performance of these methods. First, we used data from the National Survey of Fertility Barriers (N = 1,666) to estimate a model predicting marital quality based on characteristics of women and their husbands. Second, we conducted a simulation based on these data testing the five methods and compared the results to estimates where the true value was known. We found that the maximum likelihood and multiple imputation methods were advantageous because they allow researchers to utilize all of the available information as well as produce less biased and more efficient estimates.

Effects of divorce on Dutch boys' and girls' externalizing behavior in Gene × Environment perspective: Diathesis stress or differential susceptibility in the Dutch Tracking Adolescents' Individual Lives Survey study?

The effects of divorce on children's behavioral development have proven to be quite varied across studies, and most developmental and family scholars today appreciate the great heterogeneity in divorce effects. Thus, this inquiry sought to determine whether select dopaminergic genes previously associated with externalizing behavior and/or found to moderate diverse environmental effects (dopamine receptors D2 and D4, catechol-O-methyltransferase) might moderate divorce effects on adolescent self-reported externalizing problems; and, if so, whether evidence of gene–environment (G × E) interaction would prove consistent with diathesis–stress or differential-susceptibility models of environmental action. Data from the first and third wave of the Dutch Tracking Adolescents' Individual Lives Survey (n = 1,134) revealed some evidence of G × E interaction reflecting diathesis–stress but not differential susceptibility. It is intriguing that some evidence pointed to “vantage sensitivity,” which are benefits accruing to those with a specific genotype when their parents remained together, the exact opposite of diathesis–stress. The limits of this work are considered, especially with regard to the conditions for testing differential susceptibility, and future directions are outlined.

A genetically informed study of associations between family functioning and child psychosocial adjustment

Research has documented associations between family functioning and offspring psychosocial adjustment, but questions remain regarding whether these associations are partly due to confounding genetic factors and other environmental factors. The current study used a genetically informed approach, the Children of Twins design, to explore the associations between family functioning (family conflict, marital quality, and agreement about parenting) and offspring psychopathology. Participants were 867 twin pairs (388 monozygotic; 479 dizygotic) from the Twin and Offspring Study in Sweden, their spouses, and children (51.7% female; M = 15.75 years). The results suggested associations between exposure to family conflict (assessed by the mother, father, and child) and child adjustment were independent of genetic factors and other environmental factors. However, when family conflict was assessed using only children's reports, the results indicated that genetic factors also influenced these associations. In addition, the analyses indicated that exposure to low marital quality and agreement about parenting was associated with children's internalizing and externalizing problems and that genetic factors also contributed to the associations of marital quality and agreement about parenting with offspring externalizing problems.

Parental depression and offspring psychopathology: a children of twins study

BACKGROUND

Associations between parental depression and offspring affective and disruptive disorders are well documented. Few genetically informed studies have explored the processes underlying intergenerational associations.

METHOD

A semi-structured interview assessing DSM-III-R psychiatric disorders was administered to twins (n=1296) from the Australian Twin Register (ATR), their spouses (n=1046) and offspring (n=2555). We used the Children of Twins (CoT) design to delineate the extent to which intergenerational associations were consistent with a causal influence or due to genetic confounds.

RESULTS

In between-family analyses, parental depression was associated significantly with offspring depression [hazard ratio (HR) 1.52, 95% confidence interval (CI) 1.20-1.93] and conduct disorder (CD; HR 2.27, CI 1.31-3.93). Survival analysis indicated that the intergenerational transmission of depression is consistent with a causal (environmental) inference, with a significant intergenerational association in offspring of discordant monozygotic (MZ) twin pairs (HR 1.39, CI 1.00-1.94). Logistic regression analysis suggested that the parental depression-offspring CD association was due to shared genetic liability in the parents and offspring. No intergenerational association was found when comparing the offspring of discordant MZ twins [odds ratio (OR) 1.41, CI 0.63-3.14], but offspring of discordant dizygotic (DZ) twins differed in their rates of CD (OR 2.53, CI 0.95-6.76). All findings remained after controlling for several measured covariates, including history of depression and CD in the twins' spouses.

CONCLUSIONS

The mechanisms underlying associations between parental depression and offspring psychopathology seem to differ depending on the outcome. The results are consistent with a causal environmental role of parental depression in offspring depression whereas common genetic factors account for the association of parental depression and offspring CD.

Marriage and Divorce: A genetic perspective

Marriage is considered one of the most important sources of social support that an individual receives as an adult. Although hypotheses have been formulated as to why individuals may dissolve a marriage, the determinants of marital success or failure are still relatively unknown. Behavioral geneticists have found that both marriage and divorce are, in part, genetically influenced. The goal of this research was to determine the degree of shared genetic and environmental variance between the two marital statuses. Participants were 6,225 twin pairs from the Vietnam Era Twin Registry. Data were obtained on marital history, and if the individual was no longer married, how the marriage ended. Univariate analyses were performed to determine the extent of genetic and environmental influences each of the marital statues (i.e., marriage and divorce), followed by a novel bivariate analysis to test the shared variance between marriage and divorce. Results from this analysis revealed that the two different marital statuses were influenced by entirely distinct genetic and environmental factors.

The effect of the transition to parenthood on relationship quality: an 8-year prospective study

This longitudinal study examined the effect of the birth of the 1st child on relationship functioning using data from 218 couples (436 individuals) over the course of the first 8 years of marriage. Compared with prebirth levels and trajectories, parents showed sudden deterioration following birth on observed and self-reported measures of positive and negative aspects of relationship functioning. The deterioration in these variables was small to medium in size and tended to persist throughout the remaining years of the study. Mothers and fathers showed similar amounts of change after birth. The amount of postbirth deterioration in relationship functioning varied systematically by several characteristics of the individual, the marriage, and the pregnancy itself. In a group of couples who did not have children, results indicated more gradual deterioration in relationship functioning during the first 8 years of marriage without the sudden changes seen in parents, suggesting that the results seen in the parent sample may be due to birth.

Effects of parental divorce on marital commitment and confidence

Research on the intergenerational transmission of divorce has demonstrated that compared with offspring of nondivorced parents, those of divorced parents generally have more negative attitudes toward marriage as an institution and are less optimistic about the feasibility of a long-lasting, healthy marriage. It is also possible that when entering marriage themselves, adults whose parents divorced have less personal relationship commitment to their own marriages and less confidence in their own ability to maintain a happy marriage with their spouse. However, this prediction has not been tested. In the current study, we assessed relationship commitment and relationship confidence, as well as parental divorce and retrospectively reported interparental conflict, in a sample of 265 engaged couples prior to their first marriage. Results demonstrated that women's, but not men's, parental divorce was associated with lower relationship commitment and lower relationship confidence. These effects persisted when controlling for the influence of recalled interparental conflict and premarital relationship adjustment. The current findings suggest that women whose parents divorced are more likely to enter marriage with relatively lower commitment to, and confidence in, the future of those marriages, potentially raising their risk for divorce.

Intergenerational transmission of childhood conduct problems: a Children of Twins Study

CONTEXT

The familial nature of childhood conduct problems has been well documented, but few genetically informed studies have explicitly explored the processes through which parental conduct problems influence an offspring's behavior problems.

OBJECTIVE

To delineate the genetic and environmental processes underlying the intergenerational transmission of childhood conduct problems.

DESIGN

We used hierarchical linear models to analyze data from a Children of Twins Study, a quasiexperimental design, to explore the extent to which genetic factors common to both generations, unmeasured environmental factors that are shared by twins, or measured characteristics of both parents confound the intergenerational association.

SETTING

Participants were recruited from the community and completed a semistructured diagnostic telephone interview.

PARTICIPANTS

The research used a high-risk sample of twins, their spouses, and their young adult offspring (n = 2554) from 889 twin families in the Australian Twin Registry, but the analyses used sample weights to produce parameter estimates for the community-based volunteer sample of twins. Main Outcome Measure Number of conduct disorder symptoms.

RESULTS

The magnitude of the intergenerational transmission was significant for all offspring, though it was stronger for males (effect size [Cohen d] = 0.21; 95% confidence interval, 0.15-0.17) than females (d = 0.09; 95% confidence interval, 0.05-0.14). The use of the Children of Twins design and measured covariates indicated that the intergenerational transmission of conduct problems for male offspring was largely mediated by environmental variables specifically related to parental conduct disorder (d = 0.13; 95% confidence interval, 0.02-0.23). In contrast, the intergenerational transmission of conduct problems was not because of environmentally mediated causal processes for female offspring (d = - 0.09; 95% confidence interval, - 0.20 to 0.03); a common genetic liability accounted for the intergenerational relations.

CONCLUSIONS

The mechanisms underlying the intergenerational transmission of conduct problems depend on the sex of the offspring. The results are consistent with an environmentally mediated causal role of parental conduct problems on behavior problems in males. Common genetic risk, however, confounds the entire intergenerational transmission in female offspring.