Personality From Age 10 to 16 years. A Four-Wave Cohort Study of Development and Sex Differences in the Big Five and Its Facets

Recent years have witnessed an increased interest in personality development in childhood and adolescence. However, population-based longitudinal studies that examine self-reported personality traits and their facets during these critical developmental periods are scarce. Here, we test the disruption hypothesis, which suggests deviations from standard patterns of personality maturation during adolescence in certain personality domains. Our study extends existing knowledge by examining development and sex differences in self-reported conscientiousness, agreeableness, neuroticism, and their facets from childhood to adolescence. Utilizing the Big Five Inventory, we collected four waves of personality data (ages 10, 12, 14, and 16 years) from a representative birth cohort of Norwegian children (<i>N</i> = 805). Our results predominantly support the disruption hypothesis, showing declines in conscientiousness and agreeableness across sexes from age 12, with an increase in neuroticism observed solely for girls. The findings further demonstrate that maturation disruptions vary at the facet level, suggesting a complex developmental process.