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RESEARCHERS

The Science of Adult Sibling Dynamics: Why the Old Roles Never Left

3 the researchers behind it — Most families never vote on who's the favorite, the screwup, or the reliable one — the roles just harden, usually before anyone in them could argue ba

Brigham Young University

Alexander C. Jensen

Known for:Research on sibling influence, differential treatment, and social comparison from adolescence through later life

Key findings

  1. 2013

    With Whiteman, Fingerman, and Birditt, Jensen showed young adults continue to perceive differential parental treatment well into their twenties and thirties — the sense that 'life isn't fair' between siblings doesn't end with childhood. ↗

  2. 2022

    With Apsley, Thackeray, and Shoaf, Jensen surveyed 491 adults and produced the first study of sibling social comparison in mid- to later life, finding it linked to both more depressive symptoms/conflict and, in the same data, greater sibling closeness. ↗

  3. 2025

    With Jorgensen-Wells, Jensen meta-analyzed nearly 19,500 participants across dozens of studies and confirmed parental favoritism is real and patterned — parents on average favor daughters, more conscientious children, and, on measures of autonomy and control, older siblings. ↗

Purdue University

J. Jill Suitor

Known for:The Within-Family Differences Study — a long-running research program on parental favoritism and its effects across adult siblings' lives

Key findings

  1. 2013

    With Gilligan, Kim, and Pillemer, studying 341 adult children in 137 later-life families, Suitor found a father's — but not a mother's — current favoritism predicted tension between adult siblings, especially among daughters. ↗

  2. 2013

    Tracking mothers' favoritism over time, Suitor and colleagues found it to be remarkably stable across years — a mother's 'favorite' rarely changes — meaning perceived favoritism is a durable feature of the family system, not a passing phase. ↗

  3. 2016

    Modeling data on 381 older mothers and their 1,421 adult children, Suitor and colleagues found that how similar a child's values are to the mother's — more than the child's achievements — was the strongest predictor of maternal favoritism and disfavoritism. ↗

University of Cologne, Institute of Sociology and Social Psychology

Karsten Hank

Known for:Large panel-data research on sibling estrangement and family estrangement across adulthood

Key findings

  1. 2023

    Using six years of panel data on 5,729 adults, 28% reported at least one episode of estrangement from a sibling, and estrangement was best predicted by structural features of the sibling relationship and disruptive family events like parental divorce or death. ↗

  2. 2024

    Follow-up work on the same panel finds that adults who are estranged from a family member report lower life satisfaction and more depressiveness than those who are not — estrangement is not a neutral or cost-free outcome. ↗

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