Twins’ Agreement on Negative and Positive Life Experiences

Most studies of life experiences rely on retrospective self-reports due to the major advantages of this method of data collection. However, some clinicians and researchers express doubts regarding the reliability of self-reports about lived experiences. One option to explore reliability is to assess two or more sources of information, a procedure usually labeled agreement, which consists of the comparison of a self-report (main participant) and a collateral report, to assess whether both reporters describe the same experiences (concordance) and/or to explore whether the collateral confirms the experiences reported by the main participant (corroboration). We studied concordance and corroboration of positive and negative life experiences in 47 pairs of adult twins (N = 94), both genders, 18–50 years of age; 32 pairs were monozygotic. Participants were asked about their own life experiences (to assess concordance) and about their twin’s life experiences (to assess corroboration). Overall agreement between twins was quite acceptable, although it was heterogeneous across items and/or domains. For instance, physical abuse presented a moderate kappa for concordance, while sexual abuse achieved a poor kappa. Corroboration presented globally higher kappa than concordance, suggesting that twins seem to be especially good source of collateral information. Remarkably, when valence (i.e., positive vs. negative experiences) was analyzed, concordance and corroboration were higher for positives experiences than for negative ones. Our results suggest that self- and collateral-reports are reliable means of assessing life experiences, which has important implications for future research.