Sociology Ph.D. Dissertations


Blended Families and Their Influence on Sibling Relationships and First Union Formation

Date of Award


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)



First Advisor

Kara Joyner (Committee Co-Chair)

Second Advisor

Gary Oates (Committee Co-Chair)

Third Advisor

Susan Brown (Committee Member)

Fourth Advisor

Alfred DeMaris (Committee Member)

Fifth Advisor

Neil Englehart (Other)


Over the last fifty years, the proportion of children living with a single parent or a stepparent has increased dramatically due to high rates of divorce, non-marital childbearing, and cohabitation. Research continues to suggest that children from two biological parent families fare better than children from other types of families with respect to a variety of outcomes. A small but growing literature on blended families suggests that conventional measures of family structure fail to capture adequately the complexity of living arrangements for children who reside with two biological parents and one or more half-siblings. This nascent literature suggests that these children do not reap the full benefits of living with two biological parents. In fact, they more closely resemble children who reside with a stepparent. Studies examining blended families have focused on cognitive, educational, and psychological outcomes during childhood and adolescence but they have not examined sibling relationship quality or union formation. Nor have they been able to explain fully the relative disadvantages of children in blended families. Finally, studies have yet to address the implications of family boundary ambiguity for the measurement of blended families. This study uses the incomplete institutionalization perspective to address four questions: (1) How discrepant are the family structure reports of siblings who reside in blended families versus other arrangements?; (2) Does sibling relationship quality in blended families differ from that in other families?; (3) Is growing up in a blended family associated with union formation patterns in young adulthood (e.g., the transition to a first co-residential union)?; (4) Does sibling relationship quality mediate the association between family structure and first union formation? Using data from waves one and four of the National Longitudinal Study of Adolescent Health (Add Health), I find that six percent of all sibling pair reports of family structure are discrepant and that discrepant reports are more likely to occur in complex families, particularly blended cohabiting families. Siblings in blended families do not significantly differ from siblings in other family types in their reports of affection. Individuals from blended families form first co-residential unions at younger ages than their counterparts from two biological parent families. Sibling relationship quality is not associated with the rate of first union formation; however, poor sibling quality increases the likelihood of cohabitation and good sibling relationship quality increases the likelihood of marriage.