Is your elder sibling smarter? Blame parents

Elder siblings have higher IQs and better thinking skills as they receive more mental stimulation from parents in their early years, according to a new research. First-borns score higher than their siblings in IQ tests as early as age one, researchers from University of Edinburgh have found. They said that first-born children received more support with tasks that developed thinking skills. Researchers said the findings could help explain the so-called birth order effect, when children born earlier enjoyed better wages and more education in later life.

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.