Does birth order define your health? Study of 50,00,000 families reveals disease link

Siblings may share the same parents, home and childhood, yet grow up with strikingly different health risks.A study analysing medical insurance records from more than 50 lakh American two-child families has found that birth order is associated with differences in the likelihood of developing several diseases later in life.Published in Nature Health, the study led by Andrey Rzhetsky, Edna K. Papazian Professor of Medicine at the University of Chicago, examined 418 medical conditions.Researchers found statistically significant associations between birth order and 150 conditions, suggesting that early-life experiences may leave lasting fingerprints on health.The findings showed that firstborn children were more likely to be diagnosed with neurodevelopmental conditions and allergies, while second-born children had higher odds of certain substance use disorders, migraines, gastrointestinal conditions and infections.Among the conditions more frequently associated with firstborns were autism, attention-deficithyperactivity disorder (ADHD), Tourette's syndrome, obsessive-compulsive disorder, depression, anxiety, asthma and food allergies.