1. Objectifs

Intentions :
«The main objective of the present study was to examine the concurrent, cross-sectional, and longitudinal associations between the quality of the twin-sibling relationship and the quality of the relationship with the best friend. Second, we were interested in examining whether reciprocal sibling relationships that reflect more egalitarian interactions, such as twin relationships, are associated with the quality of twins’ friendship relationships, both concurrently and longitudinally.» (p. 126)

2. Méthode

Échantillon/Matériau :
This study uses «191 MZ [monozygotic] twin pairs (100 female pairs) and 286 DZ [dizygotic] same-sex twin pairs (71 female twin pairs) participating in this study were part of a population-based sample of 464 MZ and same-sex DZ twin pairs from the greater Montreal area, Canada, who were recruited at birth from between November 1995 and July 1998.» (p. 127) Twins in the sample used were 13 years and 14 years old.

Type de traitement des données :
Analyse statistique

3. Résumé

«Latent path analyses showed that, for positive relationship features, the stability from age 13 to 14 was stronger for the twin relationship than for the friendship relation. There were, however, no differences in zygosity (or sex) in regard to these stability patterns. Twins (both MZs and same-sex DZs) not only share a joint history since before they are born, but they also spend much more time with each other than they do with peers. […] More interestingly, cross-lagged associations showed that MZ and same-sex DZ twins who reported more positive features in the relationship with their co-twin also experienced more positive features in the relationship with their best friend a year later. […] Since our findings also show that positive social interactions between twin siblings are stable over time, such consistent exposure to a positive sibling relationship may thus create a stable context for positive social learning, regardless of zygosity. Negative aspects of the friendship and twin relationship quality were also relatively stable over a 1-year period. In contrast to what we found for positive relationship features, there were no significant cross-lagged associations between negative features of the sibling relationship and the relationship with the best friend.» (p. 132)