Study Discovers That Younger Siblings Benefit from Later School Entry of Their Older Siblings

Having a high-achieving older sibling helps children, especially those from socioeconomically disadvantaged families, succeed academically, a new study led by Yale University reports.

Using data from public schools in North Carolina, a team led by Yale sociologist Emma Zhang found that children whose birthdays come shortly after the kindergarten start deadline—and thus are among the oldest in their class—tend to perform better academically. From younger classmates.

For those students who have younger siblings, the study found that their success in turn has a positive effect on those siblings once they reach middle school—especially among children from disadvantaged families.

“We establish the causal effect of having an academically successful sibling on a student’s academic results,” said Zhang, associate professor of sociology in the Yale College of Arts and Sciences and lead author of the study. “While most previous studies posit that these indirect effects occur across socioeconomic settings, our findings demonstrate that they are much stronger among disadvantaged households than in privileged households, which has important implications for how we think about inequality and the policies we implement to address it. ”

The study published in American Journal of SociologyCo-authored by Philip J. Cook of Duke University and Boh Lin Tan of the University of Singapore.

The researchers analyzed a unique dataset provided by the North Carolina Education Research Data Center that correlates birth certificate information with school administrative records. Specifically, they examined four important characteristics of family background: ethnicity, maternal educational attainment, family structure, and poverty levels at school. All individuals in the data set were born before 2004, when North Carolina law allowed children born on or before October 16 to begin kindergarten before their fifth birthday.

They found that students born within two months after the termination date had higher math and reading scores by a fifth of a standard deviation in elementary school than those born later. (They found that the difference in scores diminished slightly during middle school.) For younger siblings, having an older sibling soon after a kindergarten dropout was associated with an increase in overall math and reading scores during middle school, according to the study.

The researchers suggest that by middle school, students have reached a developmental stage often fraught with uncertainty and challenges, which can make them more receptive to the influence of older siblings. When their older siblings do well in school, it can positively affect their academic performance.

The effects were greater for students in schools affected with higher levels of poverty than for students in schools with low poverty, according to the study.

Among disadvantaged families, the effect of sibling prevalence was statistically significant in all four groups studied. By contrast, among socioeconomically advantaged families, the effect was only statistically significant for children whose mothers had a high school diploma when they were born, the study found.

Zhang explained that a possible explanation for the divergent effects is that wealthy families have the resources to limit the influence of older siblings on the academic performance of younger siblings. For example, they can provide separate bedrooms for their children and afford extracurricular activities for younger siblings, allowing them to spend more time outside the home with other children, she said.

Zhang noted that advantaged families are also in a better position than disadvantaged families to deliberately delay a child’s entry into school, allowing them to take advantage of being older than their classmates and in athletics. She said policies aimed at curbing the practice could help reduce inequality between poor and wealthy households.

She said the results of the study indicate that children in disadvantaged families may be more likely to view their older siblings as role models, adding that the influence of an older sibling can be positive or negative depending on the situation.

“Our work has important policy implications, particularly in countries like the United States that have weaker social safety nets,” Zhang said. “Disadvantaged families are more likely to experience hardship than advantaged families, and the negative effects of these experiences can spill over from older siblings to younger siblings. At the same time, policies aimed at supporting disadvantaged families can yield a higher return, our study shows, Positive benefits pass from older siblings to younger siblings.”