About 80 percent of people in the United States have at least one sibling, and if yours is close to you in age, you’ve probably tried to sum up that relationship in one clean sentence and come up short. A new study of nearly 1,000 young adults suggests there’s a reason for that: siblings close in age rarely land in an easy middle ground. According to research recently published in the Journal of Social and Personal Relationships, they’re most often named as either a person’s closest relationship or their biggest source of conflict, and only rarely as something calm and in between.
A Study Built Around Whole Sibling Groups, Not Just Pairs
Most research on siblings has zoomed in on a single pair, you and one brother or sister, even though more than half of Americans with siblings actually have two or more of them, according to the same study. Psychologist Alexander C. Jensen of Brigham Young University and his co-authors, Sarah Ashby, Naomi M. Noorda, and Jennie Jasperson, wanted to see what happens when you look at someone’s entire sibling lineup at once instead of just one relationship in isolation. They surveyed 975 young adults ages 19 to 29, average age about 25, recruited from across the country, and asked each person to rate their relationship with every sibling they had, not just the one they thought of first.
The Sibling You’re Closest To Is Often the One You Fight With Most
Here’s the result that reframes how you might think about your own family: participants were more likely to name a close-in-age sibling as the one they felt closest to, and more likely to name that same kind of sibling as the one they clashed with most. Age proximity, in other words, didn’t produce lukewarm, easygoing relationships. It produced strong ones, pulled toward one extreme or the other, with comparatively few landing in the calm middle you might expect from two people who grew up sharing a house, a school, and a set of parents.
Why Nearness Raises the Stakes
The study also found that relationship quality varied more across a family’s sibling set when brothers and sisters were spaced further apart in age or split across genders. Flip that finding around and it says something useful: siblings who are close in age and the same gender tend to share nearly everything, bedrooms, friend groups, curfews, and the same parents’ attention during the same stretch of childhood. That overlap creates more chances for genuine connection, but it also creates more chances for direct comparison and competition, which helps explain why the relationship tends to run hot rather than settle into neutral.
The Extremes Don’t Stay Contained to the Sibling Relationship
Conflict with a sibling, the researchers found, was linked to worse life satisfaction, self-esteem, and self-regulation, while having at least one especially close sibling bond was linked to better outcomes even inside a family with a lot of overall variation in how well siblings got along. That pattern tracks with earlier work: a study out of Iowa State University and Purdue University, published in the journal Social Sciences, followed 495 adult children across 254 families and found that tension with a sibling predicted depression in midlife at a level comparable to tension with a spouse or a mother. The sibling closest to you in age isn’t only shaping how you feel this week. The data suggests it can shape how you feel decades from now.
None of this means something is wrong with your family if the sibling nearest your age is either your favorite person to text or the one whose name still makes your chest tighten. Based on this data, that’s the more common outcome, not the exception. What it does mean is that the relationship is worth tending on purpose, because the same closeness that makes it your best bond is exactly what makes the conflict, if that’s the version you got instead, so hard to shake loose. You may not get to choose which sibling ends up closest to you in age, but the numbers suggest that relationship rarely stays neutral for long, so it’s worth nudging toward the good extreme rather than letting the bad one take hold.
