[The sibling status effects and the personality scales of the MMPI]

The purpose of this study is to find out if the personalities of siblings are similar or different. Subjects used were Doshisha University students and members of their families, provided those families had only two children. Altogether 29 pairs of boys and their younger brothers, 47 pairs of boys and their younger sisters, 44 pairs of girls and their younger brothers, and 51 pairs of girls and their younger sisters were given the MMPI individually. Sibling status effects were found in many of the MMPI scores according to the type of sibling dyads and birth order, especially for the sibling dyad of elder brother and younger sister. Personality relationships between the first and second child showed that there were significant correlations in many MMPI scales: L, K, Pd, Pa, Pt, Sc, Si, Conflict resolution, Manifest anxiety, Repression-Sensitization, and Hostility. Among the four types of sibling dyad, the pairs of girls and their younger brothers showed the highest correlation in their personality.