Researchers examined data from the US Children of the National Longitudinal Survey of Youth. Nearly 5,000 children were observed from pre-birth to age 14. The tests included reading recognition, such as matching letters, naming names, reading words and picture vocabulary assessments.
The findings showed that advantages enjoyed by first born siblings started from just after birth to three years of age.Researchers found that parents changed their behaviour as subsequent children were born. They offered less mental stimulation to younger siblings and also took part in fewer activities.
“Broad shifts in parental behaviour are a plausible explanation for the observed birth order differences in education and labour market outcomes,” said Ana Nuevo-Chiquero