This study examined the influence of twin status (monozygotic [MZ], dizygotic same-sex [DZss] and dizygotic opposite-sex [DZos]) on friendship patterns. It examined the friendships of 60 children from 30 twin pairs, mean age 8 years, 4 months. The study sought to establish how number of friendships and degree to which these are shared vary according to twin status. Additionally, it sought to assess the children's meaning of shared friendship and to examine whether there were group differences according to twin status. Results indicated that, while number of friends did not vary, the degree to which friendships were shared was significantly associated with twin status. MZ children shared approximately 50% of their friends, DZss 25% and DZos 5%. Group patterns emerged from interviews with the children concerning shared friendships. MZ twins were characteristically positive or accepting about shared friends; DZos pairs shared fewer friends and were, therefore, less challenged by the twin situation in negotiating friendships; and DZss pairs were more diverse in their reaction with some expressing ambivalent or negative views about the twin situation and sharing of friendship. The results are presented in the light of their implications for twin children's developmental and scholastic progress.

The definition and nature of twin language has been a focus of recent studies concerned with the phenomenon. There has been a call for a tighter definition and understanding of the meaning of twin language (Thorpe et al., 2001). This article sought to identify social factors associated with the parent report of twin language and thus provide further understanding of the phenomenon. Data from 583 mothers of twins aged 25 to 59 months were analyzed using multiple logistic regression. Factors included in the modeling of parent-report twin language included social experience factors such as presence of siblings, attendance at preschool education and reports of nonverbal play. It was found that twin pairs who didn't have an older sibling, who showed frequent nonverbal play and who didn't attend preschool were more likely to have a twin language. Moreover, in the group not having an older sibling, the influence of whether twins attended preschool or not was strong and the odds ratio was 0.589 (95% confidence intervals 0.360–0.963). The findings suggest that social experience factors are important predictors of the parent reporting of twin language.

Recent plans to establish a Twinsburg Research Institute in Twinsburg, Ohio, home of the annual Twins Days Festival, are reviewed. Included among the topics under discussion were the development of an Ohio and/or national United States twin registry and the appropriate location for such a facility. Next, recent findings on chromosomal anomalies and other adverse consequences of artificial reproduction are summarized — some results are surprising and unexplained. This information is followed by further examination of epigenetic twin studies, supplementing a review in a previous issue. The last section of this article presents insightful material about twin leaders, scholars, athletes, designers and parents.