Summary: Young children with older sisters show better early language outcomes than those with older brothers.
Source: CNRS
Overview
It might seem intuitive that having an older sibling would expose a younger child to more conversation and accelerate language learning. However, multiple studies have shown that the presence of an older sibling can sometimes be associated with slower language acquisition. A recent multidisciplinary study by researchers from CNRS, AP-HP, EHESS, ENS and INSERM clarifies this issue by examining the role of the older sibling’s sex. The team found that younger children raised with an older sister develop language skills on par with children who have no older sibling, while those with an older brother tend to lag behind.
Study details and findings
The research used data from the EDEN mother-child cohort, which followed children from birth until 5.5 years of age. In total, more than 1,000 children were included in the analysis (the published report cites N = 1,154). Researchers assessed language skills at ages 2, 3 and 5.5 using standard measures that tested vocabulary, syntax and verbal reasoning. After accounting for relevant factors, the team found that children with an older brother showed, on average, a two-month lag in language performance compared with children who had an older sister. Importantly, children who had an older sister did not differ significantly from children without any older sibling.
The study also examined whether the age gap between siblings influenced language outcomes. Contrary to the authors’ initial prediction, the size of the age difference did not significantly affect language development and did not interact with the older sibling’s sex. In other words, the negative effect linked to having older siblings appears to be driven primarily by older brothers rather than by differences in age spacing between siblings.
Interpretation and future directions
The authors propose two plausible mechanisms that could explain why older brothers—but not older sisters—are associated with slower language development in younger children. First, older sisters may interact more frequently or more conversationally with younger siblings, effectively supplementing parental input when parents are less available. Second, older sisters may engage less in competitive behaviors for parental attention, allowing parents to allocate more linguistic input to the younger child. The present study cannot definitively determine which of these explanations is correct, and both may contribute to the observed pattern.
Looking ahead, the research team plans to explore cultural and geographical variations in sibling influence, investigating whether the observed effects differ across regions or cultural backgrounds. Such follow-up work could help identify social or caregiving practices that shape sibling interactions and their impact on early language development.
* The EDEN cohort enrolled families between 2003 and 2006 at the CHU hospitals in Nancy and Poitiers.
Source:
CNRS
Media contacts:
Francois Maginiot – CNRS
Image credit:
Public domain image.
Original research (summary)
The peer-reviewed article is titled “The Effect of Older Siblings on Language Development as a Function of Age Difference and Sex,” authored by Naomi Havron et al., and published in Psychological Science (closed access). The published DOI is 10.1177/0956797619861436.
Abstract (rephrased)
This study investigates how the number and characteristics of older siblings relate to a younger child’s verbal abilities, with a focus on the older sibling’s sex and the age gap between siblings. Using data from the EDEN cohort (N = 1,154), the authors tested whether having an older sister versus an older brother differentially affects language development, and whether a larger age gap might amplify or reduce any such effects. Results indicate that children with an older sister exhibit stronger language skills than those with an older brother. Contrary to the initial hypothesis, the age gap did not predict language outcomes and did not interact with sibling sex. These findings suggest that the previously observed negative correlation between number of older siblings and child language may stem largely from the presence of older brothers. The authors call for further research to uncover the mechanisms underlying these sex-based differences.