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Understanding Twins

Twins' Memoirs and Autobiographies

The lives of twins, told in memoirs and autobiographies, tell us a lot.

Key points

  • Details of identical twins' lives can tell us what affects their behaviors, which is useful information.
  • Particular environments can affect behavior in unpredictable ways.
  • Physical distance does not mean emotional distance.

Autobiographies and memoirs have important differences. An autobiography is a non-fiction narrative that documents the entire life of a writer. In contrast, a memoir is a truthful work in which an author provides recollections from a certain interval in his or her life. Some twins have written about their lives in intriguing and informative ways. These books and essays suggest new ways of thinking about twins’ similarities and differences in development. In particular, twins may highlight unique experiences that have been neglected by researchers. This information helps to refine the elusive factors explaining identical co-twin differences. This post summarizes several that I have examined, and some that warrant attention.

The idea of writing about this topic originated with an identical twin named Robert Gentle, who is originally from South Africa. I was in touch with him and his twin brother Michael a few years ago. They are a close twin pair despite living and working far apart: Robert lives in Johannesburg, and Michael lives near Lisbon, Portugal; I described the Gentle twins in an article I published in the journal Twin Research and Human Genetics in 2020. Both twins are now full-time authors. Michael has written several books, most recently Life Before the Internet: What We Can Learn From the Good Old Days. Robert just completed an autobiographical work, The Scholarship Kids: Dream Big and Fly High. I will begin with Robert’s truly spellbinding work that he calls a memoir, probably because it covers only certain portions of the twins’ lives.

Robert and Michael were born in 1957, in Cape Town, South Africa, and were considered "coloured," the designation given to people of mixed race. It was the time of apartheid, so they lived in a separate neighborhood, as did whites, Indians, and Blacks. It was the white people who enjoyed voting rights and were able to visit preferred restaurants and resources. However, the clever Gentle twins did very well in the schools they attended in South Africa and in Zambia, where they proceeded in parallel from their elementary school days to their university days in Zambia, and in France, where they studied aviation and took a course in computer programing. However, their career paths and physical closeness ended when Robert was offered a job he felt compelled to accept, given his writing interests.

Robert returned to Johannesburg as a journalist for Business Day, a position that offered exciting assignments abroad. Given this life change, he also launched a consultancy firm and wrote a popular book on business writing. Michael stayed in Paris, working in information technology, but also became a writer. Both twins are now retired and have traveled to Toulouse and Paris to revisit places of their earlier years—once again on common ground.

Separated fraternal (non-identical) twins Allison Kanter and Michele Mordkoff met one another in 2018, when they were 54. They were one of several twin pairs intentionally separated by the New York City adoption agency, Louise Wise Services (LWS). Their adoptive parents (and those of the other intentionally separated pairs) were not told that their child was a twin. The identical twins, but not the fraternal twins, were secretly studied until they turned 12 years of age. Finding unique factors linked to fraternal twin differences is more difficult than finding them for identical twins. That is because there is a confounding of different genes and different environments. However, the twins’ family structures and places of residence are worth examining—Michele was raised in New Jersey with two younger brothers, both of whom were the biological children of her adoptive parents, whereas Allison was raised in California with an older adoptive sister.

As I described in my 2021 book, Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart, Michele learned about the 2018 documentary film, Three Identical Strangers—the story of the separation of identical triplets by the New York City adoption agency and the chance reunion of three identical males—and wondered if she might be a separated twin. This was a reasonable concern, since she was born in the mid-1960s when the study was looking for twins for research participation. Michele’s concerns led her to Allison and these twin sisters established a very close connection despite living on opposite coasts of the United States. Sadly, their relationship ended when Michele passed away from cancer in June 2021. Before her loss, the twins had been working together on a memoir intended to reveal their horrific separation and to celebrate the time they enjoyed together. Allison will now finish this task on her own—I know that the final work will be a heartbreaking but insightful addition to what we know, and can know, about twins’ lives.

Other books worth reading are Separated @ Birth: A True Love Story of Twin Sisters Reunited by Anais Bordier and Samantha (Sam) Futerman, published in 2014, and Being You by separated identical twin Mary Holmes, published in 2008. Separated @ Birth describes events leading to the reunion of identical twins, Anais and Sam, born in South Korea and adopted by different families in France and the United States, respectively. Sam was an aspiring actress and placed a video of herself on the Internet that was seen by one of Anais’s friends. Amazed by the physical resemblance and matched behaviors between his friend and Sam, he encouraged Anais to meet Sam. She did, and the two women met in London as identical twin sisters, at age 25. I was happy to inform the twins of the results of their DNA test, proving that they are identical. This was captured on film; Sam had the foresight to record the process of finding her twin and their reunion, leading to a wonderful documentary, titled Twinsters.

Mary Holmes and her identical twin sister, Elaine Alin, from the United Kingdom, participated in the Minnesota Study of Twins Reared Apart. In 2014, Mary authored a fascinating book about their different lives, their reunion, and the events happening after that. The twins’ different religious backgrounds suggest that such experiences explain later attitudes. Religion played a moderate role in Elaine’s childhood home, but a major one in Mary’s. As time passed, Elaine wondered if believing in God came from freedom of choice, while Mary turned away from religion entirely. Clearly, the twins’ different experiences operated in unpredictable ways, explaining why they are hard to identify.

Other memoirs and autobiographies written by twins deserve attention. In a 2020 article in TRHG, I described the lives of identical male twins, George and Frank Engel, and Norris and Alan (Ross) McWhirter. George Engel, in 1975, and Norris McWhirter, in 1976, both described the loss of their twin, but differences between them while together were apparent. Other autobiographical works of twins include Divided minds: Twin sisters and their journey through schizophrenia by Carolyn Spiro Wagner and Pamela Spiro, written in 2005; Her: A Memoir written by Christa Parravani 2013) and Twin: A Memoir (Shawn, 2010); this sampling is not exhaustive. My chapters on the reared-apart “fireman twins,” Mark Newman and Jerry Levey from New Jersey; George Holmes and Brent Tremblay from Canada; and Oskar Stohr Germany and Jack Yufe from Germany and California, respectively, but born in Trinidad, also identify non-shared environmental factors that may explain their observed co-twin differences (Segal, 2005/2007).

It is also worth revisiting the biographical sketches/life histories of the reared-apart twins appended to the quantitative findings in the three early studies by Newman, Freeman, & Holzinger (1937), Shields (1962) and Juel-Nielsen (1965/1980), with an eye toward non-shared experiences and their impact on the twins’ subsequent behaviors.


Gentle, Michael ( 2023). Life Before the Internet: What We Can Learn From the Good Old Days. Winchester, UK: O-Books.

Gentle, Robert (2023). The Scholarship Kids: Dream Big and Fly High. Cape Town, South Africa: Melinda Ferguson Books.

Segal, N.L. (2021). Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart, Lanham, MD: Rowman & Littlefield.

Bordier, A, & Futerman, S. (2014). Separated@birth: A True Love Story of Twin Sisters Reunited.
New York: Berkley Publishing Group.

Holmes, M.E. (2008). Being You. London: Austin & Macauley Publishers Ltd.

Engel, G. L. (1975). The death of a twin: Mourning and anniversary reactions. Fragments of 10 years of self-analysis. The International Journal of Psycho-Analysis, 56, 23-40.

Wagner, P. S., & Spiro, C. (2005). Divided Minds: Twin Sisters and Their Journey Through Schizophrenia. NY: Macmillan.

Parravani, C. (2013). Her: A Memoir. NY: Macmillan.

McWhirter, N. (1976). Ross: The Story of a Shared Life. London: Churchill Press Limited.

Segal, N.L. (2005/2007). Indivisible by Two: Lives of Extraordinary Twins. Cambridge, MA: Harvard University Press.

Newman, H.H., Freeman, & Karl J. Holzinger, K. (1937). Twins: A Study of Heredity and Environment. Chicago: University of Chicago Press.

Niels Juel-Nielsen (1965/1980). Individual and Environment: Monozygotic Twins Reared Apart. New York: International Universities Press.

Shields, J. (1962). Monozygotic Twins Brought Up Apart and Brought Up Together. London: Oxford University Press.

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