A new economics study has revealed that childhood illnesses could be a key factor in why firstborn children tend to earn more than their younger siblings. Researchers from the University of Copenhagen, collaborating with a team from Sydney University, analysed decades of Danish data and found that illnesses during early years may account for the 1.9 per cent wage gap commonly observed between siblings.
Study Findings
The study examined data from 5,000 children who were given reading and picture vocabulary tests every two years. It discovered that younger siblings were two to three times more likely to suffer from respiratory illnesses, which sometimes led to hospitalisation. Children who experienced illnesses in their early years achieved lower academic results, potentially because infections diverted energy away from brain development.
Previous Research
These findings align with earlier research from the University of Edinburgh, which found that firstborns score higher on IQ tests, with the gap appearing within the first year of life. Firstborn children are also known to perform better in exams and earn more in adulthood.
Reasons for the Gap
One explanation is that firstborn children often pick up viruses at nurseries and pass them on to their baby siblings, increasing the younger siblings' risk of illness. Another factor is the difference in parental attention: firstborns typically receive more one-to-one attention during their early years, while younger siblings often have parents juggling multiple childcare responsibilities.
Parents are encouraged to ensure vaccinations are up to date and to keep sick children at home rather than sending them to nursery, to help reduce the spread of infections.
