Within-Family Differences Study 


       In 2001, Jill Suitor and Karl Pillemer began a program of research on within-family differences in parent-adult child relations with the goal of achieving greater understanding of these processes in aging families. At that time, most research on the causes and consequences of the quality of parent-adult child relationships involved between-family studies of parents' relationships with one child in the family or with all children in the aggregate. The aims of the first phase of the Within-Family Differences Study (WFDS) were to: 1) collect data from members of both generations regarding parents' relationships with each of their adult children; 2) explore the extent to which parents differentiated among their offspring; and 3) identify factors that explained why parents held preferences toward specific children.

       Guided by these aims, between 2001 and 2003 we interviewed 566 mothers ages 65-75, 130 of their husbands in person, and 773 of their adult children by telephone. In 300 families, data were collected from members of both generations. The findings based upon these data revealed that most mothers and fathers differentiate among their adult children across a wide range of relational dimensions, including providing and receiving support, preferences for future caregiving, and emotional closeness. Further, it was possible to identify characteristics of adult children and the parent-child dyad that led parents to prefer particular offspring.


       The WFDS-I was ideally suited to investigate patterns of within-family differentiation in later life; however its cross-sectional design did not allow examination of either changes across time in differentiation or the consequences of such differentiation. Thus, building on the findings from the first phase, between 2007 and 2014 we conducted the WFDS-II to examine stability and change in mothers' preferences and adult children's perceptions of those preferences, as well as their effects on mothers' and adult children's psychological and relational well-being.

       Between 2008 and 2011 we interviewed 420 of the mothers who had participated in the first phase (86% of the original 566 mothers who were living at T2). We also interviewed 826 adult children, most of whom participated in the first and second wave of interviews, and some of whom participated only in the second phase.

       Our foci in the WFDS-II were to explore the stability of the differentiation patterns revealed in the first phase of the study and investigate the consequences of differentiation on both generations, with particular interest in the experiences of mothers and their adult children when mothers faced health challenges. Using a combination of quantitative and qualitative data, Suitor, Pillemer, and Megan Gilligan (who joined the project in 2006), documented the high stability of mothers' relationships with their children across time, identified the characteristics of adult children and parent-child dyads that predicted which children would assume the caregiver role, and the salience of mothers' earlier preferences in these processes. Further, we uncovered the detrimental consequences of the violation of preferences regarding future caregivers on mothers' psychological well-being. Finally, we explored how perceptions of their parents' favoritism affected adult children's relational and psychological well-being, finding that adult children who perceived that their parents favored some siblings over others were more likely to report depressive symptoms, as well as less closeness and greater conflict with siblings.


       Taken together, the findings of the WFDS-I and WFDS-II demonstrated that among the wide-range of factors researchers have considered in the study of parent-adult child relations, parental preferences emerged as the most consistent predictor of relational and psychological well-being among the mothers and adult offspring in our panel. We expect that such preferences become even more consequential after the loss of parents in later life.

       To explore this issue, in 2019 Jill Suitor and Megan Gilligan received funding for the third wave of the project, the Within-Family Differences Study-Bereavement. In February of 2020, we will begin collecting data from the adult children who participated in the first waves of the panel to explore the role of long-term family relations in psychological well-being, physical health, and health behaviors following the death of parents. In this phase, we are bringing adult grandchildren into the project to shed light on the ways in which relationships across three generations affect health, psychological well-being, and patterns of care and support of family members, especially following the loss of grandparents.

Contributions of the Within-Family Differences Study

       The findings from the study have resulted in the publication of more than 60 articles in scholarly journals and volumes, and have received wide attention in the media. The study has been featured more than 400 times in media reports, including articles in the New York Times, the Boston Globe, the Washington Post, the Toronto Star, the AARP Magazine, and on National Public Radio. Links to media reports and scholarly publications can be found under the tabs on the WFDS web site labeled "WFDS Publications" and "WFDS in the News." A 2016 Ted Talk based upon the Within-Family Differences Study has been viewed nearly 40,000 times.


       We wish to express our appreciation for the support we have received for the WFDS. From 2001-2014 and in 2019-2020, the project has been supported by grants from the National Institute on Aging (RO1 AG18869-01; 2RO1 AG18869; 1R56AG062767-01). We also express appreciation to the Office of the Vice President for Research at Purdue University for support during the 2014-2015 academic year, and to the Office of the Executive Vice President for Research and the Office of the Provost at Purdue for funding the WFDEP Feasibility Study in 2017. Jill Suitor and Megan Gilligan also wish to acknowledge support from the Center on Aging and the Life Course at Purdue University.