At each new school year, this is a question that arises for the parents of twins and their teachers: should the twins be left in the same class or is it better to separate them? On the basis of the so-called de-twinning theory, some schools impose an almost systematic separation of twins , with the aim of making them more independent and favoring their individuality.

According to this theory, keeping twins in the same class would prevent the healthy development of their identity. Thus, according to a survey conducted in the United States , 71% of school principals believe that it is important to separate twins in kindergarten. This same survey reveals that separation is systematically carried out in kindergarten in 45% of cases, sometimes against the advice of parents and children. Thus, although 81% of the twins wanted to be integrated into the same class in the middle and large section, 58% of them are separated.

Parents who are against separation say that keeping their children in the same class would allow them to help each other and reduce their stress of going to school, especially in the early years. On the other hand, parents who are in favor of separation explain that this would allow their children to develop their own identity, reduce the risk of conflict between them and make their own groups of friends. Nevertheless, in this survey, the majority of parents (62%) do not find it beneficial to separate their children into large section and do not want this to be done. Also, 20% of parents whose twins were separated say it was at least a little traumatic for their children.

Are policies of systematic separation of twins at school justifiable? In reality, these policies are based on theories that have, to date, received no empirical foundation. Moreover, numerous scientific studies, carried out over the past two decades, call into question the practices of systematic separation of twins at school. This research provides important data on the effects of the separation of twins on their well-being and learning and can help educational teams and parents in their choice (when possible) whether or not to keep these students in a same class.

Effects on well-being

Regarding well-being at school, a study of 1,116 English and Welsh children aged 5 to 7 revealed that twins who were separated at school showed slightly higher signs of anxiety and depression than twins. having been kept in the same class. These results were confirmed in another research carried out on a sample of 2184 pairs of Dutch twins which also shows a persistence of these negative effects at the age of 7 when the children were separated at the age of 5. However, this negative effect does not persist at age 12.

Regarding the question of social relations, the hypothesis of an advantage of the separation of twins on the quality of their interactions with each other and with other children was recently contradicted by a study conducted among 1120 Quebec twins aged 6 to 12. year. Indeed, this study does not reveal any positive effect of the separation on the relationship between the twins and shows above all that the twins sharing the same classroom were slightly less socially withdrawn than those placed in different classes.

Finally, in the three studies cited, no positive or negative effect of separation could be demonstrated on behavioral problems in young pupils aged 5 to 7 years. In contrast, Garon-Carrier’s study shows that 12-year-old twin students separated into two different classes exhibited more aggressive behaviors and exhibited more attention problems than those who were not separated.

Effects on educational achievements

In terms of school acquisitions, the results of scientific studies are more mixed. For example, research by Tully et al., (2004) found a small positive effect of separating 5-year-old dizygotic twins on work engagement, but a small negative effect on the development of reading skills in the first years of acquisition.

Nevertheless, the follow-up of 5756 Dutch twins carried out by Webbink et al , in 2007, shows that keeping twins, especially those of the same sex, in the same class has positive effects on the development of their language and arithmetic skills in CE1 .

Among older students, studies by Polderman et al. (2010) on 4006 Dutch twins and White et al. (2018) on 8705 English and Canadian twins do not show any positive or negative effect linked to the separation of twins on academic achievement, cognitive skills or motivation when they are aged 7 to 16. On the other hand, a positive effect of the separation of twins in middle school on language skills has been demonstrated, but this latter effect is only observed for pairs of opposite-sex twins.

A dialogue between teachers and families

To date, research shows few beneficial effects of separating twins at school. Rather, there appear to be weak negative effects of early twin separation on anxiety, depression, arithmetic, and language in students’ early years of schooling (kindergarten and early elementary school). In addition, twins kept in the same class show better socialization skills than those who have been separated.

Later, prolonged separation during elementary school shows small but negative effects on aggressive behavior and attention in young adolescents. Currently, research indicates that most of the time, having a brother or sister in the same class is more of a protective factor than a risk factor for these children. Keeping twins in the same class could facilitate entry and the first steps in school, but also the transition to adolescence. Therefore, the research results provide empirical arguments against any policy of forced and systematized separation of twins at school.

Nevertheless, the question of the separation of twins remains complex and the antagonistic position which would consist of the implementation of a policy of systematically keeping brothers and sisters in the same class is not desirable either. Indeed, behavioral problems noted by the teaching team or problematic relationships between the twins could justify separation decisions.

All of the researchers cited conclude on the need to study situations on a case-by-case basis and that the choice of separating or keeping twins in the same class must be the result of consultation between teachers, parents and students taking into consideration the specific needs of each child as well as their behavior in class.

Author Bio: Jonathan Fernandez is a Research Professor in Cognitive Psychology at the University of Paris-Est Créteil Val de Marne (UPEC)