The mediating role of personality traits in the relationship between psychological birth order and posttraumatic growth

The aim of this study is to examine the role of personality traits in the relationship between psychological birth order and posttraumatic growth. Within the scope of the study, the direct and indirect relationships among psychological birth order (firstborn, middle child, youngest child, and only child), Big Five personality traits, and posttraumatic growth were identified. The study was designed using a relational survey model, and the analyses were conducted based on data obtained from 293 participants. The Psychological Birth Order Scale, the Big Five Personality Inventory, and the Posttraumatic Growth Inventory were used as data collection instruments. Data analyses were performed using the SPSS statistical software package and included descriptive statistics, correlation analyses, Mann–Whitney U Test, Kruskal–Wallis H Test, one-way ANOVA, independent samples t-test, and structural equation modeling analyses. Structural equation modeling analyses were conducted separately for each psychological birth order group using PROCESS Macro Model 4. The results of the correlation analyses indicated that firstborn psychological birth order scores were positively associated with extraversion, agreeableness, and conscientiousness, whereas middle child psychological birth order scores were negatively associated with agreeableness and conscientiousness and positively associated with neuroticism. Youngest child psychological birth order was positively related to openness to experience. Only child psychological birth order was found to be positively associated with neuroticism and negatively associated with conscientiousness. When posttraumatic growth total scores and subdimensions were examined, openness to experience emerged as a personality trait showing strong and consistent associations with posttraumatic growth. The results of the structural equation modeling analyses revealed that psychological birth order was not a strong or direct predictor of posttraumatic growth. For firstborn individuals, a significant total effect was observed in the "changes in philosophy of life" subdimension, while an indirect effect through conscientiousness was identified in the "changes in relationships" subdimension. For middle children, indirect effects through agreeableness and conscientiousness were found in the "changes in relationships" dimension. For youngest children, marginal indirect effect tendencies were observed for posttraumatic growth and some of its subdimensions through openness to experience. For only children, no significant direct effects on posttraumatic growth were observed; however, an indirect effect through conscientiousness was identified in the "changes in relationships" subdimension. Overall, the findings indicate that psychological birth order does not independently predict posttraumatic growth; rather, it exerts limited and context-specific effects through its interaction with personality traits. In particular, openness to experience emerged as the strongest and most consistent predictor of posttraumatic growth. These results suggest that posttraumatic growth has a multidimensional structure.