Birth order, personality, and religion: a study among young adults from a three-sibling family

Effects of birth order on personality are modest but not inexistent. However, studies do not often distinguish between two kinds of laterborns: middleborns and lastborns. In addition, some evidence suggests effects of birth order on religion. In the present study, 122 young adults from three-sibling families completed the NEO-PI-R and gave information on religion and school performance. Peer(mother)-evaluation of personality was also assessed. Middleborns seemed to represent the “rebellious” (laterborn) sibling in Sulloway's (1996) theory: in comparison to their siblings, they were less conscientious, less religious, and lower in school performance, as well as more impulsive and open to fantasy, whereas lastborns were the most agreeable and warm. In most cases, effects were similar in self- and mother-evaluation. Finally, mother ratings validated self-reported personality correlates of religion (Conscientiousness, Agreeableness, low impulsiveness and low excitement seeking) and spirituality (Openness).