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The Controversial Study of Twins and Triplets Adopted and Reared Apart

What I learned about the 1960s study of separated twins.

Key points

  • Infants twins were separated and studied in New York City in the 1960s.
  • Adoptive parents did not know they were raising a child who had been separated from a twin.
  • The twins' records remain sealed at Yale University until 2065.

The course of human life is fragile. The way our paths unfold can be drastically derailed by seemingly innocent or accidental events with unintended results. Policies carried out by people with good objectives, but who lack the foresight to consider the implications or consequences of their deeds, can inflict irrevocable damage on individuals, families, science, and society.

New York’s Child Development Center Twin Study of the 1960s and 70s took small, incremental steps toward helping unwed mothers, but its foundation quickly turned into secrets and cover-ups. Lives were fractured forever because a reputable adoption agency took the advice of a well-intentioned but misguided psychiatrist to place newborn twins apart, and welcomed an unprincipled self-interested researcher who secretly studied them. Events like these remind us that in our current climate of social media, digital record keeping and online transactions, our privacy and trust in others may be illusory. We all take reasonable risks with the institutions holding our personal information, the physicians taking our medical histories and the banks managing our finances. Any one of us could be the victim of good intentions gone awry.

In the fall of 1982, I arrived at the University of Minnesota as a post-doctoral fellow to work on the Minnesota Study of Twins Reared Apart (MISTRA). By then, the MISTRA had gained considerable stature, drawing attention from national and international scholars, students and journalists. But for a brief time during my early years in Minnesota, an older twin study was gaining attention once again. CBS’s 60 Minutes, was preparing an exposé of the Louise Wise Services (LWS) — Child Development Center (CDC) twin project. The program was intended to show how and why a group of New York City psychiatrists (mainly Drs. Viola W. Bernard and Peter B. Neubauer) and psychologists decided to "play God" by separating infant twins and tracking their development without informing the adoptive families that their children were twins. The investigative journalists also wanted to know what the scientists hoped to learn from this unique study, the only one in the world to follow separated twins prospectively from birth. Ultimately, the planned television special was canceled.

Scientists and journalists occasionally revisit this controversial study, most recently in the production of two documentary films, The Twinning Reaction (2017) and Three Identical Strangers (2018), as well as a 20/20 ABC news program (2018). This episode in twin research has gripped the public that is now clamoring for more, perhaps because the project was so unthinkable, violating not just established norms, but beliefs in the sacredness of family and faith in the integrity of scientists. People everywhere began talking about the study; at anniversary parties and birthday celebrations, I often become the center of attention because of my twin research background. Festivities were ignored as lush gardens and backyard patios become scenes of dialogue and debate. “How could this happen?” guests demanded to know. “What more can you tell us?” It has been no different among my professional colleagues. “There's so much more that needs to be written about it...” “I wondered if you have been consulted... I'd appreciate your thoughts and/or a link to something you may have written about this.”

Some elements of the secret study were shown in the two documentaries, but it is a mistake to think that the whole story has been told. There is much more to say about the twin pairs that were raised apart, as well as the inner workings of the study that 55-minute and 90-minute films cannot capture. Furthermore, aside from the omissions there was information that requires clarification. It is uncertain as to whether twins were separated for purposes of the study—some believe they were separated on the assumption that each individual twin child would enjoy undivided parental attention and develop a stronger sense of identity. These people would agree that the study came later. However, this may not be exactly what happened, an issue I explore in my new book, Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart. Another critical point is that twin research is a vital, informative and respected part of the behavioral and medical sciences. The wealth of well-conducted studies has significantly enhanced our understanding of human nature, underlined the unique challenges faced by twins and the families who raise them and suggested ways to assist twins.

The twins who have learned about their past have experienced uncontrollable anger, considerable sadness, and deep regret. Their parents have been outraged that a respected and trusted adoption agency endorsed such dishonest and deceptive practices. Everyone would have willingly raised a complete set of adopted twins or triplets had they been given the chance. LWS disregarded the requests by some parents for multiple birth children.

Upon closing in 2004, the Louise Wise Agency handed its records over to the Spence-Chapin adoption agency. At present, information may be released only to the twins by the Jewish Board of Family and Child Services (JBFCS). The data collected by the research team has been deposited in the Yale University archives in New Haven with the stipulation that it not be released until 2065. Dr. Viola Bernard’s twin-related papers have been hidden from view at Columbia University, but some have become available as of January 2021; at first, however, given the pandemic, this material could only be viewed by Columbia University faculty, students, and staff. Neubauer and his son authored a 1990 book, Nature’s Thumbprint, but many important details of their work are omitted. He only states that an “opportunity arose to follow the development of identical twins from infancy.” The Louise Wise Adoption Agency does not appear in the index or text, nor does Dr. Viola Bernard.

A few of the twins have been granted access to portions of their personal information, but it is an arduous process, requiring prior approval from several sources. Frustrated, some twins have sought legal counsel. Several attorneys are independently working on their behalf and some material, but not all, has been retrieved.


Segal, N.L. (2005). More thoughts on the Child Development Center Twin Study. ­­­ 276-281.

Segal, N.L. (2018). Twins Reared Apart From Birth; Beyond the Secret Study. Sloan Science and Film,…

Segal, N.L. (2019). Twin Studies: Through the Lens of Three Identical Strangers. Quillette., March 26, 2019,…

Segal, N.L. (September 26, 2021). Shame and Silence: The LWS Twin Studies Revisited. Quillette,…

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