Study of 700,000 volunteers finds middle children score higher on cooperation traits

Middle children tend to show stronger cooperative personality traits than their older and younger siblings, according to a large-scale study by researchers at Brock University and the University of Calgary. The researchers analyzed data from more than 700,000 volunteers to examine how birth order relates to personality. Middle children scored higher on traits associated with cooperation, including agreeableness, honesty and humility, the study found. The authors said growing up in larger families gives children constant interaction with siblings, helping them develop stronger social skills. They noted that middle children must navigate relationships with both older and younger siblings, giving them accumulated experience in negotiation and understanding others' needs. The researchers cautioned that the differences are clear at a group level but do not constitute a firm rule at the individual level, pointing to the role of genetics, education and environmental factors in shaping personality. Earlier theories had described eldest children as highly responsible and youngest children as more independent and creative, the researchers said, adding that the middle child can now be added to the literature as a "cooperation-based balancing element."