The Surprising Ways That Siblings Shape Our Lives (Susan Dominus, May 6, 2025, NY Times Magazine)
And then there are siblings. “I think the influence of siblings on each other is an area in psychology that has not nearly received the attention it deserves,” says Lisa Damour, a psychologist and author who writes about adolescence. “When we look at child development, our main frameworks have been around the influence of parents on children, and that’s the established tradition that we’ve had a hard time moving past.”
Anyone raising more than one child, Damour says, or who has a sibling, intuitively knows that sibling relationships play a powerful role in affecting who we become. “If parents are the fixed stars in the child’s universe, the vaguely understood, distant but constant celestial spheres, siblings are the dazzling, sometimes scorching comets nearby,” wrote Alison Gopnik, a developmental psychologist, in a review of a book about siblings in 2011.
A body of research has been growing in recent years that adds clarity and depth to our understanding of how significant the impact of siblings can be. Researchers have studied how siblings influence one another’s choices and life trajectories through competition; they have uncovered deeper knowledge of so-called spillover effects, the ripple effects of how one sibling’s experiences affect another’s; and they have brought rigor to bear on popular ideas about birth order. New tools of genetic research may challenge or sharpen previously held conceptions about siblings. The data set of families whose stories might shed light on some of these interactions is limitless, but one place to look is at siblings who have long fascinated me: those in families in which a surprising number of brothers and sisters have found their way to the top of the ladder of success. Some of the dynamics described in the research, in those families, might be borne out in the extreme. Siblings, at their best, can urge one another on; competing and collaborating — whether intentionally or not — they help chart the course of one another’s lives.