Science has spoken, y’all!

Meghan Overdeep
August 15, 2018

It’s plagued siblings since the beginning of time, and now science has finally weighed in on the perpetual debate over whether or not mamas treat their children differently based on their birth order.

Presumably harboring their own feelings of inequity, a team of four experts in child development at the U.S. National Institutes of Health, set out to investigate whether or not there is any scientific weight behind the anecdotal assumption that mothers can’t help but play favorites.

The results of their study, which was headed by Marc H. Bornstein, Ph.D., were recently published in Social Development. What they found are significant differences in how mothers-of-two interact with each of her children—but they have nothing to do with preference.

Maybe mama wasn’t lying after all!

“There was no observable preference for the first or second child,” Diane Putnick, a study co-author a developmental psychologist at the NIH, told Inverse. “Instead what we observed was that each relationship seemed unique.”

According to Inverse, the study involved observing two hours of interactions between 55 mothers and their first-born children when the kids were 20 months old. Years later, the same mothers returned with their second-born children when they were 20 months of age.

Researchers found that while the mothers’ beliefs surrounding parenting didn’t vary from child to child, when it came to put those values into practice, they did.  

Try as they might to apply the same parenting rationale to both their kids, it didn’t appear to work out for the moms in question.  Inverse reports that mothers engaged in 15% more play with older children, and younger siblings received roughly 4% more praise and 9% more physical affection.

The results appear conclusive: birth order alone has no impact on how a mother treats her children. Instead, researchers believe that differences in parenting are actually based on the personality of each child. And to make things even more complicated, the study also pointed out how personality is affected by birth order. For example, first-born children are often more sociable than second-born children, due to what Putnick suggested to Inverse might be “years of undivided attention before a sibling is born.”

“I think that maternal practices differ between their two siblings because individual children have unique characteristics,” Putnick explained. “As much as parents might try to treat sibling children similarly. Their children’s individual needs may dictate different parenting.”

So there you have it!