How does birth order change siblings’ family relationships and futures?

A new study looks at childhood dynamics, family structure and the lasting impacts both have on American life

For the nearly 80% of Americans who grew up with at least one sibling, that relationship is likely to be more enduring and impactful than nearly any other.

But birth order, perceived parental favoritism, age difference and other factors all influence how siblings get along and other aspects of their relationships for their entire lives.

That’s among the findings of a report issued this week by the Survey Center on American Life. In “Emerging trends and enduring patterns in American family life,” which is a large, nationally representative survey, researchers looked at marriage, family structure, household chore division, the role of faith and more.

“Few aspects of childhood have a more unique and enduring impact” than brother-sister relationships, said Daniel A. Cox, the center’s director and a senior fellow in polling and public opinion at the American Enterprise Institute.

“When we interviewed people 60 and 70 years old, we were still seeing effects of birth order,” said Cox. “That shows how powerful those experiences are.”

Most Americans who grew up with at least one brother or sister said they had a reasonably close relationship with siblings. Just 22% said they were either not too close or not at all close to their siblings.

Middle children, surrounded on both sides by others, reported having the closest relationships. Almost half of middle children said that, compared to 40% of eldest children and 35% of the youngest.

Men whose parents divorced during their childhood felt more distant from siblings than those who grew up in intact households. Divorce didn’t affect sibling relationships for females in the same way.

In addition to divorce, time and different life journeys can create distance, too. While most Americans describe at least somewhat close relationships with their siblings growing up, just 51% say they are very or completely satisfied with the relationship they now have with siblings.

Parents have a lot of unofficial say in whether families stay close. “Simply put, Americans who are very or completely satisfied with the relationship they have with their parents are very likely to feel the same about their relationship with their sibling,” the report says.

Parents’ pets

Perceived favoritism — “Mom always liked you better” — is a factor that impacts family relationships, in both the long term and short term. Roughly 4 in 10 survey respondents with siblings said that growing up, their parents had a favorite child — and it wasn’t necessarily them.

When they perceived favoritism growing up, adults who were polled said they felt less close to both their siblings and their parents. And they were more likely to say they felt lonely during their childhood than did those who said their parents didn’t have a favorite child.

Men were less likely to perceive parental favoritism than women, 35% to 45%. They were also more likely to report being the favorite child. While one-third of men felt favored growing up, that was true of just 25% of women.

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Those raised in households where parents divorced were more apt to see favoritism than those in intact households. Financial or emotional stress in those homes seemed to make it harder to guard against favoritism, Cox said.

Middle children were least likely to say they were the favorite child at 17%, compared to 27% of first-born and 38% of last-born.

“That’s not a surprising finding,” said Cox. “Both the eldest and youngest have time with parents without any siblings around. The middle don’t; they’re never the only one there.”

The report highlights lots of research showing favoritism is bad, perhaps permanently, for kids. It hurts self-esteem, weakens sibling bonds, makes people feel less connected socially and is really hard on parent-child bonds — even if the child in question was the perceived favorite.


But true to the adage that little is never all good or all bad, while middle children were the least apt to say they felt lonely growing up, they often did feel overlooked or forgotten.

Feelings of loneliness in childhood, not surprisingly, were most often expressed by someone who grew up as an only child, particularly female only children. The study finds “little evidence” that this loneliness persists as they become adults.

“Only children report having roughly the same number of close friends as those who grew up with siblings and are just as satisfied with their social lives today,” the report said.

On the other hand, an only child also got a lot of parental attention and resources to themselves, as well as expectations put on them. An only child is more apt to say expectations he or she would go to college were high, Cox said.

Finding support

Family life has changed over the decades, becoming less tied to large institutions like churches or community service or family dinners. Parenting focuses much more on individual development, playing to a child’s skills and interests.

Still, Cox said parents are actually dedicating more time to parenting, which seems like a contradiction.

“My theory — and this goes beyond the data — is that we as parents in this country are devoting more time and resources to personal, individualized development as opposed to more communal time together playing games or in civic activities or having family dinner,” he said.

That may play into growing reports of loneliness, he said, as families do fewer communal activities and children are left with less of a sense that they’re an important part of a bigger community.

If the village that helped raise a child has gotten smaller, where did children go for help and support growing up? There are some differences based on race and ethnicity, religion and gender. But overall, moms topped that list.

“Close to half say moms,” said Cox. “That’s much, much more than fathers. They were more likely to turn to close friends and siblings than their father.”

The exception to that, he added, is white evangelical men. Of those, 17% said they looked to their fathers for help with a personal problem.

Just 30% of Asian Americans say they would turn to their moms, compared to 39% of Hispanics, and 42% of both Black Americans and white Americans. But Black men were the most likely to turn to their mothers during their formative years, at 46%.

White women were more likely than white men to ask friends for help growing up. And white men were twice as apt as white women to say they turned first to their father when they had a problem, 12% vs. 5%.

For Black and Hispanic women, sibling relationships are really important. In fact, no other group is more likely to rely on their siblings than Black women, Cox said.

Correction: An earlier version incorrectly stated that Daniel A. Cox’s middle initial is C.