Certain publicly held beliefs, including many that are endorsed or perpetuated by psychotherapists and educators, are based on fiction rather than fact. One such belief, that is neither validated by research nor supported by clinical observation, is the contention that twins (multiples) should be separated when they attend school.

Most American schools generally have policies about the placement of twins, often ones that enforce the mandatory separation of multiples. Educators have endorsed separating twins in pre-kindergarten or kindergarten because of the assumption that separate classroom placement promotes intellectual, emotional, social, and physical development—an assertion that lacks empirical evidence (Hay & Preedy, 2006). In some schools there are no laws or written policies, but there is a general philosophy, handed down for decades, that twins should be separated. Recently, some states have enacted “twin laws” that allow parental input in the together or separate classroom placement of their children, and other states have sponsored bills to promote legislation that allows parents of twins to have a voice or have adopted resolutions to maintain a flexible policy regarding the classroom placement of twins (www.twinslaw.com). Nevertheless, many schools still mandate or encourage the separation of twins.

The assumption that twins should be separated has to do with a misunderstanding that physical separation encourages the development of individual identity and independence; namely, that eventually a twin must achieve separation from parents as well as from the co-twin. There is a very strong bond that develops between twins, and a policy that demands separation completely ignores the importance of their unique attachment. As one twin broadcasts the emotion she experiences, her co-twin resonates with that expression of emotion. This process of affective (emotional) resonance creates a partnership in affective interaction, conversation, or contagion, and forms the basis of later empathy—the sharing of emotion (Nathanson, 1992).  Twins are tuned into the displays of affect on each other’s face and such “contagion,” as Nathanson (1992) and Basch (1983) have described, becomes a source of shared emotion. Living in a “fellowship of feeling” (Nathanson, 1992) twins are also subject to distraction in their interaction with each other and this contagion is not best dealt with through imposed separation but instead by learning skills that will help them to manage the affect broadcast by the other (Nathanson, 1992). This is the case with all children, of course, but is more pronounced in twinship. For example, if one twin is distressed and crying, the co-twin, through affective resonance, may emulate that emotion. Learning to maintain one’s own emotional integrity in the face of another’s strong emotion, while still maintaining emotional contact, fosters individuality and a separate sense of self (Gary David, Ph.D., personal communication). Maintaining one’s person as an individual, rather than promoted by imposed physical separation is instead based on how multiples are treated by the adults in their lives, and how they are guided toward emotional independence rather than interdependence. A focus on twins as individuals rather than as a unit, whether or not they share the same bedroom or classroom, is what fosters an integrated sense of self, rather than the contrived use of mandatory separation and imposed emancipation.

The bond between twins cannot be mistakenly divided: an attempt to divide them artificially will focus their attention on the separation rather than what needs to be learned. Considering that multiple birth children have little experience of separation prior to starting school, these children may find separation traumatic if school represents their first real experience of being apart (Hay & Preedy, 2006). For example, the more confident-appearing twin may develop anxiety-related symptoms without the organizing presence of her counterpart, or distress may be triggered by not knowing what or how the other is doing. Thus, rather than foster the development of individuality, mandatory separation may instead activate fear or distress.

In defense of togetherness, many studies have found that non-separated twins maintain the emotional and intellectual resources that allow them to thrive. A longitudinal study found that in the 2nd grade non-separated twins scored higher on language skills than those who had been separated, with an even larger difference for same-sex pairs (Webbink, Hay, & Visscher, 2007).  In another longitudinal study, reading scores in non-separated twins were higher than those who had been separated (Tully, Moffitt, Caspi, Taylor, Kiernan, & Andreau, 2003). Behavior problems, as rated by mothers and teachers, were more prominent in separated pairs at age 7, than non-separated ones, and no differences in academic achievement were found between the non-separated and separated group (Leeuwen, can den Berg, van Beijsterveldt, & Boomsma, 2005).

Parents must recognize that they have a choice when it comes to classroom placement of their twin children, have confidence about their convictions, and acknowledge the importance of using their intuition and emotional responses regarding what is best for their children. An arbitrary policy about what is “right” for children should inform, but never undermine, what a parent feels is in their best interest. Parents should also be informed by conversations, both individually and together, with the twins themselves.

(For information about my books, please see my website www.marylamia.com)


Basch, M. (1983). Empathic understanding: A review of the concept and some theoretical considerations. Journal of the American Psychoanalytic Association, 31, 101-126.

David A. Hay & Pat Preedy, (2006). “Meeting the Educational Needs of Multiple Birth Children,” Early Human Development, 82, 397-403.

Nathanson, D. (1992). Shame and Pride: Affect, Sex, and the Birth of the Self. New York: Norton.

Tully, L.; Moffitt, T.; Caspi, A.; Taylor, A.; Kiernan, H.; and Andreou, P.  (2003), What effect Does classroom separation have on twins’ behavior, progress at school, and reading abilities? Twin Research, 7, 115–124.

van Leeuwen, M.; van den Berg, S.; van Beijsterveldt, T.; and Boomsma, J.  (2005).  Effects of twin separation in primary school. Twin Research and Human Genetics,8, 384–391.

Webbink, D.; Hay, D.; and Visscher, P. (2007).  Does sharing the same class in school improve cognitive abilities of twins?Twin Research and Human Genetics,10, 573–580.

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