Overview

• A large-scale study involving over 700,000 participants examined the relationship between birth order, family size, and personality traits.
• Middle children scored the highest on traits linked to cooperation, such as agreeableness and honesty-humility, followed by youngest, firstborn, and only children.
• The findings suggest that growing up with more siblings fosters slightly higher levels of cooperative personality traits on average.
• Researchers found that while the number of siblings was the primary factor, birth order also had a modest impact on personality traits.
• The study controlled for variables like socioeconomic status and upbringing, showing that the trends remained consistent across diverse groups.