broad shifts in parental behavior from first to latter-born children is a plausible explanation for the observed birth order differences in education

As early as age one, latter-born children score lower on cognitive assessments than their siblings, and the birth order gap in cognitive assessment increases until the time of school entry and remains statistically significant thereafter

xperts have warned any results are generalities, which may or may not translate to individual families.

Researchers from the University of Edinburgh, the Analysis Group and the University of Sydney found that children who were born first typically scored higher on IQ tests than their younger siblings.

Researchers found that parents changed their behaviour as subsequent children were born. They offered less mental stimulation to younger siblings also took part in fewer activities such as such as reading with the child, crafts and playing musical instruments. Mothers also took higher risks during the pregnancy of latter-born children, such as increased smoking.

Economists at the University of Edinburgh, Analysis Group and the University of Sydney examined data from the U.S. Children of the National Longitudinal Survey of Youth, a dataset collected by the US Bureau of Labor Statistics.