Kids who grow up with a big sister may be more successful in life, a new study suggests. Having a big brother, not so much.
Researchers studying toddlers and their older siblings found that big sisters were far more likely than big brothers to spend time playing with and reading to their younger sibs, activities that promote child development, according to a new report published as a working paper through the Center for Global Development in Washington, D.C.
“We know that kids with parents who are more educated have better vocabularies and that’s particularly true with a more educated mother," said study co-author, Owen Ozier, an associate professor of economics at Williams College in Williamstown, Massachusetts. “What we see in our study is little kids with a big sister, rather than a big brother, have child development scores that make it look like their mom had several more years of schooling.”
A lot of research on child development focuses on the parents’ role in teaching skills to their children, said study co-author Pamela Jakiela, an associate professor of economics at Williams College.
But the researchers suspected that siblings might be playing a bigger role than they’d been given credit for, especially when parents are tied up with work or tending crops, Jakiela said.
To explore the impact of having an older sibling around, the researchers studied 552 households in rural Kenya that included 699 toddlers growing up with a single older sibling aged 7 to 14. To get a sense of who was providing the most stimulation to the toddlers, the researchers surveyed the children’s parents. They asked how many activities — such as singing, reading and playing — various household members engaged in with the toddlers. The researcher focused on those activates because they can help build vocabulary and motor skills.
On average, it turned out that older sisters engaged in more stimulating activities with their younger siblings than any other household member. That was not the case with older brothers.
“There is a literature in anthropology suggesting that well beyond our sample in Kenya, girls spend something like twice as much time as boys do on their care responsibilities,” Ozier said. “Brothers, if not paying attention to younger sibs, have different chore responsibilities, for example tending to animals, and may also have more free time.”
Parents were also asked about their education levels and their socioeconomic status.
The toddlers were tested to determine the size of their vocabularies — both active and passive — and also to see how far along they were in developing fine motor skills, such as being able to draw specific things.
When they analyzed all the data, the researchers found that having an older sister, but not an older brother, significantly improved the toddlers’ vocabulary and fine motor skills.
“The Kenya study shows pretty clearly that toddlers with an older sister end up with better vocabularies and fine motor skills than those with an older brother,” said Javaeria Qureshi, an associate professor of economics at the University of Illinois at Chicago and a research fellow at the Harvard Kennedy School's Women and Public Policy Program. Qureshi was not involved with the study.
What’s not clear is how comparable the Kenyan experience is to that in the U.S., Qureshi said. “I suspect the difference between growing up with an older sister versus an older brother is not as stark here as it is in developing countries,” she added.
Still, Qureshi said, “girls do spend a bit more time looking after their younger siblings, though boys lately have been catching up.”
Qureshi said she suspects we may be seeing more of the gender split playing out during pandemic times in the U.S., especially among families with lower incomes, because with schools closed and grandparents not able to do as much babysitting because of infection concerns, more child care may be falling to older siblings.
“Unlike many higher income parents who have the option of working from home, more parents in lower income households work jobs that can't be done from home requiring them to rely on their older children for child care," she said.
“While there’s good reason to focus on parents, it looks like we’ve been missing a pretty important piece of what goes on in people’s homes,” Qureshi said. “It looks like sibling relations may be much more important these days since people are spending so much more time at home. It will be very interesting to see how this plays out across family income and race.”