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When Do Twins First Notice Each Other?

A key question.

Parents and teachers are very concerned with twins and twin relations. While there are some helpful guidelines in dealing with such issues, I would argue that most decisions should be made on a case-by-case basis. Twins in their own way tend to signal to parents and others what is best for them. This leads to the question: When do twins first start to become aware of one other?

I would like to address this topic with reference to a classic twin study. The work, titled Twins: A Study of Three Sets of Identical Twins With Thirty Charts, was conducted by Dorothy Burlingham in 1952. Her study provides detailed descriptions of three young identical twin pairs, two females and one male. Consequently, this article also focuses on the situation of identical twins.

Interestingly, Dorothy Burlingham was born into the famous Tiffany family, the last of four children. Her father, Louis Tiffany was an artist and decorator and the heir to Tiffany & Co., founded by his own father. He is best known for his Tiffany lamps. His first two daughters, Julia and Louise, born in 1887, were identical twins, making them the likely source of Burlingham’s interest in twins. She seemed to feel envious of the close relationship these two older sisters shared (Burlingham, 1989). She was also aware of the widespread fascination that twin children inspired, even among people who already knew twins or had twins in their families. However, she suggested that older twins lack this appeal (Burlingham, 1952, p. 8).

During the war, Burlingham and Anna Freud founded the Hampstead Nurseries, which was a residential home for children between 10 days and 10 years of age. The nursery was home to four sets of identical twins, two sets of non-identical twins and one set of non-identical triplets. Three sets of identical twins were picked for observation (Burlingham, 1952), but it is unclear why the other pairs were not included in the study. The three twin pairs were Bessie and Jessie, Bill and Bert, and Mary and Madge.

Bessie and Jessie arrived at the Hampstead Nurseries when they were four months old. Bill and Bert were also four months old when they were transferred to the Hampstead Nurseries. Mary and Madge came at the age of three years and seven months. Burlingham presents many interesting details about the twins’ lives, her work is worth reading in full. I will, however, present selected findings concerning the twins’ early relationship with one another. It is important to bear in mind that many of these observations do not apply to all twins, and that their behaviors were filtered through the eyes of the attending nurses.

Bert first noticed Bill at age seven months, when he smiled at his brother, although Bill did not respond. At eight months, when they were in the same cot, Bert would fall asleep and Bill would disturb him to the point that separation was sometimes warranted. Jessie and Bessie became aware of one another at age eight months when Jessie placed her hand in Bessie’s cot. Bessie repeated this behavior toward Jessie one month later. These early observations were unavailable for Mary and Madge who arrived at the nursery at an older age.

It is likely that twins’ awareness of one another starts sooner than seven or eight months of age. An article by the late doctor, T. Berry Brazelton, observed that at age three to four months, an infant identical female twin seemed disoriented when her sister was removed from the room. When this happened, she stopped moving or feeding when she heard her sister’s voice (Brazelton, 1980). Research shows that infants as young as six months of age show social interest in one another, but as indicated this can occur even earlier for twins (Brownell, & Brown, 1992; Eckerman, & Peterman, 2001).

Based on each twin pair’s evolving relations, Burlingham concluded that twins experience more intense rivalry than non-twins. She noted that some parents try to alleviate the situation by severing the twin relationship, sending one twin away to be raised elsewhere. However, she did not cite a source for these very unusual decisions with which she disagreed. She stated: “This is an inadequate method of solving the situation. Twins cannot avoid the difficulties which are inherent in their twinship, just as ordinary children cannot help being influenced by the fact of their being an eldest, youngest or a middle child” (p. 88). She stressed that when twins maintain a healthy tie to the parent this can help keep co-twin dependence and identity in proper perspective.

This article was adapted from a large one, “Justifying Separate Experiences for Twins: Dorothy Burlingham’s Classic Twin Study,” currently in press in the journal Twin Research and Human Genetics.


Brazelton, T.B. (1980). “It’s Twins.” Redbook Magazine, 60, 83-84.

Brownell, C.A., & Brown, E. (1992). Peers and play in infants and toddlers. In V. B. Van Hasselt (Ed.) Handbook of Social Development: A Lifespan Perspective. pp. 183-200. Boston, MA: Springer.

Burlingham, D.T. (1952). Twins: A study of three sets of identical twins with 30 charts. London, UK: Imago.

Burlingham, M.J. (1989). The last Tiffany: A biography of Dorothy Tiffany Burlingham.

New York, NY: Atheneum.

Eckerman, C. O., & Peterman, K. (2001). Peers and infant social/communicative development. In G. Bremner, & A. Fogelman (Eds.). Blackwell Handbook of Infant Development. pp. 326-350. Malden, MA: Blackwell. 326-350.

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