The Twin Relationship Questionnaire:? Testing a Five-Factor Model from Early to Middle Childhood

Twins' relationships evoke critical dilemmas for parents and teachers regarding raising and educating their twins. The current study provides comprehensive psychometric information about the Twin Relationship Questionnaire (TRQ; Fortuna, Goldner, Knafo, 2010) as examined in nine samples, using mothers' and fathers' reports on 1,560 pairs of twins, tested in five measurement points from age 3 to age 9. On half of the subsamples, we conducted principal component analyses (PCA), whereas on the other subsamples, we conducted confirmatory factor analyses (CFA). Five factors were found in the PCA and confirmed by the CFA: conflict, closeness, dependence, dominance, and rivalry. All scales showed adequate internal consistencies and corrected item-Total correlations. Correlation matrixes between scales demonstrate a triad of conflict, rivalry, and dominance scales, as opposed to the dyad of closeness and dependence. As evidence for the TRQ's reliability and validity, we report the degree of agreement between mothers and fathers, the 10-month stability of mothers' reports, and the associations of the TRQ subscales with experimentally assessed prosocial behaviors between the twins at age 6.5, and with the twins' reports on their closeness at age 11. The replication of the findings across ages and raters reinforces the reliability and validity of the questionnaire.