CORNELL (US)—Whether the golden child or black sheep, siblings who sense that their mother consistently favors or rejects one child over others are more likely to show depressive symptoms as middle-aged adults, new research shows.

Earlier studies have shown that parental favoritism among siblings negatively affects mental health and often triggers behavioral problems in children, teens, and young adults, but the survey of 275 Boston-area families is the first to show that such harmful effects persist long into adulthood.

“Perceived favoritism from one’s mother still matters to a child’s psychological well-being, even if they have been living for years outside the parental home and have started families of their own,” says Cornell University gerontologist Karl Pillemer, who codirected the study reported in the Journal of Marriage and Family.

“It doesn’t matter whether you are the chosen child or not, the perception of unequal treatment has damaging effects for all siblings,” he adds. “The less favored kids may have ill will toward their mother or preferred sibling, and being the favored child brings resentment from one’s siblings and the added weight of greater parental expectations.”

Favoritism may be difficult for mothers to avoid, however, as the researchers found that 70 percent of moms surveyed named a child to whom they felt closest and only 15 percent of children saw equal treatment by their mothers. Similarly, 92 percent of children and 73 percent of mothers specified a child with whom the mother battled most frequently.

The study, which controlled for family size, race and other factors, drew on interviews with 275 mothers in their 60s and 70s with at least two living adult children and also surveys of 671 offspring of the women.

In addition to questions about emotional closeness or excessive conflict with a particular child, mothers and children were asked about the mother’s expectations for who will care for her when she becomes ill or disabled. When mothers designated a child as her caregiver, all children suffered greater depressive symptoms, though the children’s perceptions of their mother’s preference did not relate to their mental health.

The findings could lead to new therapies for practitioners who work with later-life families, Pillemer says. “We have a powerful norm in our society that parents should treat kids equally, so favoritism can be something of a taboo topic. If counselors can help older parents and adult children bring some of these issues into the open, it may help prevent family conflict from arising.”

Additional researchers from Cornell and Purdue collaborated on the work.

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