After close to two years as an only child, my son is still adjusting to life with his 4-month-old sister. But while there have been plenty of bumps, I've had no reason to doubt that the sibling relationship will enrich both of their lives —and now a new study confirms it.

Although research has long shown the positive role of older siblings in their younger siblings' lives, a report published last month in the journal Child Development proves little brothers and sisters positively affect their older siblings' empathy abilities, too.

In a statement, co-author Sheri Madigan, Canada Research Chair in Determinants of Child Development, says, “Our findings emphasize the importance of considering how all members of the family, not just parents and older siblings, contribute to children's development."

For the longitudinal study, researchers examined 452 sets of ethnically diverse sibling pairs in Canada between the ages of 18 and 48 months by videotaping interactions in the family homes and collecting questionnaires from the mothers. They gauged empathy by observing both siblings' facial and behavioral responses to an adult play-acting distress.

By assessing the responses 18 months later, researchers were able to determine that the empathy skills of older siblings improved the longer they had adjusted to life with a little brother or sister.

“The influence of younger siblings has been found during adolescence, but our study indicates that this process may begin much earlier than previously thought," says Madigan.

There was just one notable exception: Younger brothers of little sisters didn't appear to inspire the same kind of empathetic maturation. To understand the reason behind that, they said more research is needed.

This latest report is in line with the findings presented in the book The Eldest Daughter Effect, which the authors previously told Motherly explains how big sisters are primed for leadership roles later in life.

“They take responsibility, first for themselves—'Don't worry, mama, I can dress myself,' and then for their siblings— 'Don't worry, mama, I will look out for them,'" the authors write. “Taking responsibility, being diligent and dutiful, thus becomes second nature."

As hard as this may be to believe for those of us refereeing a dozen sibling disagreements per day, it certainly is a welcome reminder that our kids are better for it.

[This post was originally published March 7, 2018.]