Abstract
The purpose of this study was to investigate the personality differences between identical twins that their mothers perceive, and characterize the mothers who subjectively create either more or less personality differences between them. In Study 1, fifty-four mothers with three to six year-old twins (37 identical and 17 fraternal) filled out a questionnaire. In Study 2, ten twin mothers (7 identical and 3 fraternal), who also participated in Study 1, underwent semi-structured interviews. The main findings were as follows: Identical twin mothers perceived personality differences of their twins according to their birth order, while fraternal twin mothers did not. And those identical twin mothers who perceived more personality differences between their twins tended to describe each with more personality terms and daily behaviors, when characterizing each twin. On the other hand, those identical twin mothers who saw less personality differences inclined to contrast the twins each other, and describe each with fewer personality terms.
