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Recollections and Reflections on the Reimer Twin Case in Canada: Interview with Dr H. Keith Sigmundson/Tribute and Twin Research Review: Remembering John L. Hopper; Nonhuman Primate Twinning/Human Interest: The Accidental Twins film; Different Looking Identical Twin Newborns

Published online by Cambridge University Press:  20 December 2024

Nancy L. Segal*
Affiliation:
Department of Psychology, California State University, Fullerton, California, USA
*
Corresponding author: Nancy L. Segal; Email: [email protected]

Abstract

Dr H. Keith Sigmundson co-authored a seminal article (with the late Dr Milton Diamond) that revealed the truth about a highly controversial twin case. Specifically, the genitals of an infant male monozygotic twin were accidentally destroyed during a medical procedure performed to alleviate his difficult urination. The child’s parents were advised to physically and psychologically transform their twin son into a girl. Occasional reports about the case indicated that the plan was successful, but some members of the medical community were doubtful. An interview with Dr H. Keith Sigmundson, for the purpose of obtaining his unique perspective on this case, is presented. The interview is followed by a tribute to our late twin research colleague, Dr John L. Hopper, of Melbourne, Australia. A review of research on nonhuman primate twinning, an overview of a 2024 documentary film, The Accidental Twins, and a story of different looking identical twin newborns are also provided.

Type
News, views and comments
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of International Society for Twin Studies

Recollections and Reflections on the Reimer Twin Case in Canada: Interview with Dr H. Keith Sigmundson

Dr H. Keith Sigmundson is co-author with the late Dr Milton (Mickey) Diamond of a now classic 1997 paper describing a famous twin-related case. In 1966, a monozygotic (MZ) eight-month-old infant male twin, Bruce Reimer, was accidentally castrated during a circumcision procedure at a hospital near his home of Winnepeg, Canada. The twins’ parents, Ron and Janet Reimer, were advised by Dr John Money, of Johns Hopkins University, in Baltimore, to physically transform their child into a girl and to raise him as such. They heeded his advice — but over the years it was clear that the procedure and rearing practices were failing miserably. However, Dr Money’s writings and lectures gave no suggestion of that, indicating instead that the case was a clear success. Dr Diamond, whose tribute I authored in a previous issue of Twin Research and Human Genetics (Segal, Reference Segalin press), questioned that conclusion. Diamond spent many years searching for someone who could reveal the truth and finally found Dr H. Keith Sigmundson, in Canada.

In August 2024, I attended a two-day memorial service for Milton Diamond, held in Honolulu; Diamond was a faculty member at the John A. Burns School of Medicine, at the University of Hawaii. While there, I obtained contact information for Dr Sigmundson. I was well aware of Sigmundson’s contribution to a seminal 1997 paper with Diamond and had heard him reveal his knowledge of the case in a riveting program produced by Dateline NBC. Dr Sigmundson and I met over Zoom on August 24, 2024 (with input from his partner, Dr Gwen Kalansky), when I returned from Hawaii. Below are excerpts from my interview, edited for clarity. I have designated KS as Keith Sigmundson (see Figure 1), NS as Nancy Segal, and GK as Gwen Kalansky. Given the length of the interview, the usual sections that include twin research reviews and human interest stories have been shortened.

Figure 1. Dr H. Keith Sigmundson. Courtesy: Dr Sigmundson.

Interview

KS: I was in medical school, just out of my internship year in 1966. The case (Reimer twins] became front-page news in Winnipeg and there was a lot of talk about it in the medical school. The staff [that served the community] said we had to find somebody to take this on. The family had gone to Kelowna, British Columbia, to have a new start because they were still trying to follow what John Money was advising, and they wanted to give it their best shot. Well, it turned out that they didn’t make it there and returned to Manitoba where I was a psychiatrist at a Child Guidance Clinic. I was told that I had to take on this case.

The child [renamed Brenda] was identified by the school system as just totally misfitted. And, of course, it only became clear a little later that she was; at that time, she was the subject of this experiment by John Money.

NS: So, she contacted this Child Guidance Center? Is that how it happened?

KS: Yes. I, being the head of the center, was told by the head of pediatrics at the University of Manitoba, of which I was also a member, that I had to take it on. I would lead a team to be assembled. I went about it to the best of my ability; Brenda was nine at the time.

I had three or four people in total to work with. We made the decision that in order to give her an identification figure in play therapy and to try to get to know her, there should be a woman psychiatrist. And I was interested in doing an evaluation report every six months, although we met regularly. We had a child development specialist, an endocrinologist, a pediatric endocrinologist, and others. It was such a celebrated case. Nothing really developed because there was no way that the child was doing well — not functionally, not academically, not socially. Eventually, the BBC in London, heard about it, and it was reported to me that there was this team of people photographing or videotaping her in the back lane, going to the toilet. The other girls kicked her out of the girl’s washroom, and they called her names. She didn’t look like a girl. She didn’t act like a girl. And the other girls certainly recognized she was not one of them.

NS: The BBC came to Canada and filmed her. And you didn’t know about this?

KS: Well, no. They came. Eventually, they came to me and said, we would like to do this legitimately. I gave them an interview about all that we knew at that time. But I was instructed or encouraged and even warned by my team, who said, ‘Your whole career is gone. You’re going to be “killed” because Johns Hopkins will kill you.’ I tried to keep as low a profile as I could, but I did promise to give this man an interview. And it was broadcast in the United Kingdom, and it’s been broadcast in Germany and in the Scandinavian countries. But I made him sign a letter saying he would never allow it to be broadcast in North America. I was cautioned that patient confidentiality is essential.

NS: But you never gave the BBC permission to do that [filming]. They just did it?

KS: They just did it. I didn’t give them permission to do anything. I was more an observer of this process than I was a director. People were getting in touch with Dr Money to ask him what was going on here in Manitoba, and he just totally ignored it. He didn’t want to have any part of it. It became evident that he only wanted to know what he wanted to know and to put that in his papers. People were saying to me, you have to write this up. I said, no, I want to just make the patient feel comfortable. I’m going to have all the information documented, but the idea that I was going to be the tip of the spear, for this particular purpose — of exposing what I subsequently recognize as fraudulent misrepresentation of all the facts that were evident — was not what I wanted. However, there had developed a coterie of disciples who all were buying into him [Money] and were supporting him 100%. So, what happens next? I become the director for the province’s Child and Adolescent Psychiatry branch, developing a program for community outreach all over the province. And then I was the head of the inpatient unit at the Department of Pediatric Psychiatry at the University of Manitoba. Then I got elevated to the position of provincial psychiatrist in Manitoba, which is partially policy and partially program development. But I maintained my academic standing by lecturing and taking on students, and I was running the inpatient unit at the children’s hospital. But I got recruited because I was on a couple of national boards in Canada. It took me a long time to agree to go to British Columbia, but it was a bigger fishpond and more important than Manitoba.

NS: So, through all of this, were you still associated with the Child Guidance Center?

KS: Yes.

NS: And how long did you work with the Reimer child?

KS: I had assigned a couple of the women psychiatrists who were younger and full of enthusiasm initially. They either moved on to other things, and eventually there was an elderly woman who was in her 60s, very kindly. She kept seeing Brenda and I gave her supervision even when I had moved to British Columbia. I would meet with her regularly. And then I got appointed as the Director of Psychiatric Services for the province of British Columbia, and Mickey Diamond got hold of one of my former staff — Doreen Moggey — who said Mickey is looking for you. I said, I knew that because he had gotten ahold of me and he kept on writing to find out the truth.

She [Moggey] had been one of the people who had been corresponding with John Money. I did agree to chat with Mickey, but I had been told that getting involved with Mickey was really nuts.

NS: What was Micky writing and where was it published?

KS: Mickey was putting notes in the journals, looking for somebody who knew about the case. When he finally got ahold of me, he asked, ‘Do you know what’s happening with this case?’ By that time, I had gone onto two totally different areas of interest, but Mickey and I had this conversation on the telephone when I was in British Columbia. And I said, okay, I really understand because I was very empathetic and had been following the case — and because (when Brenda was 14), a very vigorous psychiatrist with strong opinions by the name of Sheila Kantor, said you’ve got to. You’ve got to just tell him, you can’t let him go on like this.

Eventually, Brenda’s father told him what happened. She was, by that time 14 years old. I had been off the case when she was age 13, except that I had arranged for this woman to see him. Well, I guess she didn’t continue to see him during that interlude. But eventually I was convinced [to become involved again]. I said, I’ll go back to the case involving Brenda — now renamed David after he’d had a series of 18 operations to try to build a phallus. And he was now involved with a woman [Jane].

When I went to talk to him, he was living with Jane. She had just had a baby, which everybody was accepting as David’s child. So, he had legitimacy.

NS: But it wasn’t David’s child, was it?

KS: No, no. She was pregnant at the time they got together, but it looked so appropriate or possible. When I talked to him by this time, he had become reasonably articulate. He had received some money and he had a wagon, like a van, with speakers and carpeted on the inside. He was a very popular fellow. And as you may have seen on some of the [TV] programs, he was quite attractive.

NS: Yes, yes.

KS: He was saying I’m mad enough at John Money. And I convinced him to come forward. And that’s when I arranged with the university for a studio, with a film person who was going to tape the interviews that I was doing. I was told I couldn’t let Mickey ask questions, that I had to do all the talking. But at that point in time, I was convinced by Mickey that I had to do this. So, we interviewed David and his wife and his mother. We tried to get everybody’s history, but then subsequently, when I went back to try to get the films from British Columbia, they were gone — but I had the audio. So, I ended up paying a woman to transcribe it all so that at least I had factual backup in the event that this went south.

KS: Mickey started to write more about it, and we corresponded back and forth. This is not my field of expertise, but he needed me; I felt bad that I was such a poor partner. But I proceeded and went along. With this information, he prepared most of the work, and all I had to do was verify it. He wrote the paper, and we submitted it everywhere. Each journal sent us a letter back, saying it was too controversial.

NS: Really?

KS: Eventually a journal by the name Archives of Pediatrics & Adolescent Medicine agreed to publish it. But by that time, everybody had seen it [the manuscript], but nobody wanted to do anything with it. The American Medical Association had a lot of members who believed that what was going to happen was indeed a firecracker that would go off. And so, by the time it was published, the day it was, it hit the front page of every newspaper in the western academic world.

NS: I remember.

KS: Of course, it rocketed me into fame. Indeed, it did cause me some political difficulty where I was because I had a socialist government, and I was not giving them socialist advice. I had become an associate professor of psychiatry at the University of British Columbia by that time. I did all the calls from all over, interviews forever, and all the programs. I became quite enthusiastic because David was becoming quite friendly at that point in time — he was enthusiastic about this. And we went together to these conferences — Mickey and Connie [Mickey’s wife], my partner Gwen and I, and David and Jane [David’s wife]. There was a conference in Montreal where there was a big fight between the disciples of John Money.

NS: But I want to hear about what happened. I mean, there’s a lot of rumors, and I think it’s true that John Money came over and slugged Mickey once.

KS: That was at an earlier conference before my time. When he [Mickey] was first presenting, he was just a junior at that point. Mickey and I never discussed it because he dismissed it.

[Note: John Money had published early findings in a book, Man & Woman, Boy & Girl, in which he stated that the twin situation was progressing well (Money & Ehrhardt, Reference Money and Ehrhardt1973). Nine months later, Money chaired the Third Annual Symposium on Gender Identity, held in Dubrovnik, Yugoslavia. Mickey Diamond attended, although he was neither a presenter, nor an invitee. Diamond challenged Money’s results, stating that the data to support the success of the twin’s sex reassignment and gender change were not available. Money yelled out an epithet directed at Diamond, then hit him. Diamond did not return the blow. He also claimed he had no recollection of a physical attack by Money during this exchange (Colopinto, Reference Colapinto2013).]

Of course, we had been on either Dateline or both of the programs here in Canada, W5 and another one, which I’m blocking on right now. And I got a call from the Oprah Winfrey Show. But again, there was so much controversy and they also said David would have to agree to come. I think this is before David got really enthusiastic. But they wanted to be sure that I had David in line, that he would come, as well. My lust for glory was not enough to be able to discuss it, even with David.

NS: What happened at the Montreal conference?

KS: It was mostly his [Money’s] disciples getting up and arguing with Mickey, not me, because it’s his area of expertise.

NS: But you were at the conference, too.

KS: Oh, yeah. We are on the stage at a table, with David. There were questions from the floor. David couldn’t answer any of the questions that they were posing.

GK: I do remember there were a lot of John Money supporters in the audience and that a lot of them got up and were touting John Money’s intelligence and how he was right. And I thought — you idiots.

NS: Were you harassed, Keith, on your own?

KS: No.

NS: New topic — did Mickey stay in touch with the family?

KS: Yes, with David and Janet, David’s mother. After John Colapinto [author of As Nature Made Him, 2013] got all the information he went away to write the book. He asked Mickey and I whether we wanted any profit, and we both said, absolutely not. And as a result, David got a fair amount of money from the book sales. And his twin brother [Brian], who really felt as if he should have received some of that money, was quite angry with David. He eventually went on to commit suicide.

NS: I know they said Brian was schizophrenic. Is that true?

KS: You know what? I think people throw that word around very liberally. The idea that he was schizophrenic is, fundamentally no — not in my opinion. I mean, he was really angry and he felt as if he’d been there and he’d been subjected to all the things David had, and he wasn’t getting anything. Well, David promptly took the money, and he squandered it into wonderful investment deals. The true story of somebody who wins the lottery three years later — they don’t have any [money]. He lost his job and he had a job in a union, which in this country, is a pretty valuable thing. They would have had to do something to get rid of him unless he walked away himself.

He did not want to take his testosterone because it made him feel funny. In any event, he became quite pretty and very effeminate. So, I was told that on one particular occasion, after he had lost all his money — and this is hearsay — David and Jane were in a restaurant and a waiter came up and took an order from Jane and then said, ‘What would your son like?’ And I think they broke up shortly after that. This is a guess on my part, but I think that was probably indicative of the way the relationship was at that time. He had no money. And when she first met him, of course, he’d gotten the first settlement from the court case and the Canadian medical protective. But then he couldn’t get a job — he had to go and live in his parents’ basement. And of course, he was not doing well. I was in British Columbia, and Gwen was still practicing here in Manitoba.

I phoned around to a number of my colleagues, ten or fifteen. I said I need to find somebody to see him. Gwen phoned around to everybody who was taking private patients, and there was no one who would accept him. I did arrange for a psychiatrist to see Janet, and she was seen for years, but she could never reconcile the fact that it was her problem — because she’d made the decision that John Money could go ahead.

On Christmas Day, 2004, at age 38, David took a gun and went out on a field, and committed suicide. His life was a total tragedy.

NS: Of course, it was. Are you still in touch with the family?

KS: No, I’m not at all. You see, I was not really in touch as much as my colleagues who were assigned the case, who would have been in daily or regular contact. My role was to review the case twice a year. David would tell me afterwards, he says, ‘Those were the worst days of my life.’ I mean that you had to go and sit in an office with me, and be asked many questions, even as friendly as I was. He was definitely not a happy guy.

NS: In one of the films I’ve seen, there was some discussion that John Money would film the two twins as children, naked and in compromising positions. Is that true?

KS: Well, I heard it from others that it was true. And David did say that it was true that they were asked to do that. He would describe all kinds of crazy things like that. But then after I saw the film Three Identical Strangers, I could certainly see how they would want to film the twins together and keep a record. That went on for a period of time. He [John Money] was certainly coaching Janet from Baltimore in the early years. And Janet was trying her very best to do everything that was going to make it work, although she would later say it wasn’t working.

It was never working to her mind.

NS: I’m surprised, Keith, that you say that David told you about these compromising scenes that John Money photographed. Because in one of the documentaries, he is asked about that, and he says he doesn’t remember. But Brian remembered. And David said he was grateful that he doesn’t remember because it would be too difficult for him.

KS: I think that’s true, and I do know that. But I think that he had told one of my colleagues earlier in discussions that that had happened. So, when I got it from the psychiatrist and then it was reinforced, then I accepted it as true. And it was very much in keeping with John Money as far as I was concerned. So, I was easily persuaded to believe it.

NS: I was amazed that Janet kept photographs of her male identical twins. There are a couple of pictures in which there are two little baby boys. I’m amazed that she kept those. Where did she keep them? What if they were discovered? You know, I mean, while they were trying to change Bruce into Brenda.

KS: Yeah, well. I guess she was really working with this guilt. And it’s very common for that culture to keep baby pictures, unlike in most cultures. (The Reimer family was of the Mennonite faith and deeply religious.) So, I believe she probably had them all along.

NS: Of course, everybody wants baby pictures, but in this case, where they’re trying to tell David he’s a girl — or Brenda she’s a girl — what if Brenda discovered those photographs? I always wondered about that.

Now, how did John Colapinto get involved in all this?

KS: He wrote an article in the Rolling Stone on this case. He either interviewed Mickey or he interviewed me, and then he wrote the article and then Dateline NBC did a show. But it was the article he wrote — this is only from my memory.

NS: What about the father? The father didn’t seem to take much interest in speaking. I’m sure he was devastated, but what was the father doing through all of this?

KS: The father, to the best of my recollection, was a carpenter. A tradesman. He had a good reputation. But he was not social, he was a very quiet, demure guy. The mother was the one who did all the talking while he was there. But I gather that [psychiatrist] Sheila Kantor convinced him that he had to tell David that he wasn’t Brenda.

NS: I remember that in the Dateline NBC piece — David said that he was so relieved to hear this. People thought he’d be angry, but he was relieved, and he said something like, ‘You’re the crazy ones. I’m not crazy.’

KS: That’s right. I mean, it’s dead right? I mean, at no time was he ever convinced that he was a girl by anything that anybody did. Including our best efforts.

NS: I’ll tell you, it’s still one of the most amazing cases, Keith. You know, I’ve done twin research for so many years. And this case was just one of the most extraordinary. You know, when I was in graduate school at the University of Chicago in the 70s and 80s, this case would come up as proof or good evidence that you could change the gender identity of a young child.

KS: Gwen and I would travel, and we would meet medical students from Europe in Zanzibar because they were doing some work in African countries and virtually taking over a hospital. And they were absolutely fascinated because for many of them it was new information. And then they would say, what happened for all this time, over 20 or 30 years, that it was not widely known as absolute medical chicanery?

NS: Your paper with Mickey came out in 1997.

KS: Well, we first submitted it in 1993. I’m pretty sure it was that long. I again don’t know for sure, but I’m sure it got rejected and revised and revised again and rejected again.

NS: You don’t have any of those rejection letters, do you? I would love to see them.

KS: I didn’t keep any of that because once again, I don’t even have a file that I didn’t end up giving to John Colapinto.

NS: Well, it’s still a very amazing case. I mean, absolutely amazing. And what always struck me as so unfair is that John Money continued to enjoy a good reputation. He had his supporters and he got research grants. I mean, I could not believe it.

KS: More important — Johns Hopkins eventually got onto him. I was told his office was now in the basement. It’s the kind of politics that goes on at that level. And just an aside here is that after Mickey’s obituary in the New York Times, I had six people contacting me, saying that they wanted to talk to me, including you. You came later because you went through Connie [Mickey’s wife]. I had signed a contract with people in Great Britain because they were following up on this case in another way, and because I had signed the contract, I told them I’d have to check with the person that I’d signed with before I could talk to them. She eventually said, go ahead and talk to anybody you like.

NS: So just one more quick point before we go. You said that as far as you’re concerned, Brian was not a schizophrenic. Do you think that he suicided because of depression? One of the documentaries mentioned schizophrenia.

KS: It was depression.

NS: And do you think David also suicided due to depression?

KS: Oh, yes. Depression. As far as he was concerned, his life was finished. It was over. He had nothing going for him. And I would be hard pressed to say that it was anything except just overwhelming despair. But I hadn’t talked to him now for a number of years at that point.

NS: Thank you, Keith, this has been very helpful, as well as insightful.

KS: Thank you, Nancy.

Tribute and Twin Research Review

Remembering John L. Hopper (1950–2024)

John L. Hopper was known to just about everyone who conducted twin research. His rich body of work is certainly familiar to every member of the International Society for Twin Studies (ISTS) and to readers of Twin Research and Human Genetics. His findings have been cited widely.

John was born in Australia on May 20, 1950. He received his Bachelor of Science degree in 1974 from Monash University, and his PhD degree in 1980 from La Trobe University, both in Melbourne. He was a distinguished scholar in the fields of genetic epidemiology and statistical genetics. Among his many achievements were his appointment as Senior Principal Research Fellow (one of the first nine Australian Fellows chosen by the National Health and Medical Research Council), in 2007, and Head of the Breast Cancer Unit in the Center for Epidemiology and Biostatistics, at the Melbourne School of Population and Global Health. Not surprisingly, John authored over 1000 articles and delivered hundreds of conference presentations.

On September 28, the final day of the 2024 International Twin Congress, in Assisi, Italy, John chaired (remotely) a session titled ‘Twin Research on Clinical Genetics and Chronic Disorders’. He presented a paper within that session titled, A Replication Twin Study of Breast Cancer Risk Factors. His choice of topics fits with his appointment as Head of the Breast Cancer Unit in the Melbourne School of Population and Global Health. On October 28, the day of his passing, he had chaired the first day of a conference titled, ‘Why Study Mammographic Density’.

John will be missed by those who knew him, but he left us a lasting legacy through his papers, chapters, and company. I have fond memories of John and look forward to sharing them in a special tribute planned for this journal. The ISTS committee is planning a session in his honor to be held at the ISTS Congress in Sri Lanka, August 12−24, 2025.

Sources. The Age, https://tributes.theage.com.au/obituaries/526020/john-llewelyn-hopper/?r=https://tributes.theage.com.au/obituaries/theage-au/

Wikipedia, https://en.wikipedia.org/wiki/John_Hopper_(scientist); and Scientific Program of the ISTS, 2024, https://www.twinscongress.com/scientific-programme/

Nonhuman Primate Twinning

Primate litter size was examined using life history data for 155 primate species and 794 boreoeutherian mammals (third superorder of placental mammals) with reference to the evolution of twinning. This project was carried out by Jack H. McBride and Tesla A. Monson, researchers at Western Washington University and Yale University respectively (McBride & Monson, Reference McBride and Monson2024). Primate origins were placed at 60−70 million years ago, at which time twinning occurred. The researchers asserted that giving birth to singletons as a reproductive strategy most likely co-evolved with longer gestation, larger brain size, and larger body size in both human and nonhuman primates, leading to singleton births early on. In humans, twinning currently occurs at a relatively low, but stable frequency. In contrast with nontwins, multifetal primate twinning is associated with a relatively smaller brain, smaller body size, shorter gestation period, and rapid growth. These findings align with the negative relationships observed between litter size, body size, and the other named characteristics. Implications for human evolution and directions for future investigation were suggested.

Human Interest

The Accidental Twins (Film)

A new documentary film, The Accidental Twins (2024), was released by Laberinto Productions in Colombia, South America. Directed by the celebrated Alessandro Angulo Brandestini, the film takes viewers on a tour of two identical switched-at-birth male twin pairs. The accidental exchange went undetected for 25 years until two of the ‘twins’, Wilbur and William, moved to Bogotá for work and someone mistook William for Jorge, a twin in the other pair. The film has been ranked 4/10 globally on Netflix. Brandestini presented an excerpt and discussed his work at ISTS’s film session in Assisi, Italy, in September 2024. Additional information about the twins’ amazing story can be found in the book, Accidental Brothers (Segal & Montoya, Reference Segal and Montoya2018), available in both English and in Spanish.

Different Looking Identical Twin Newborns

Twin girls, Sophia and Adriana, were born to Danielle Marple, of Venice, Florida on October 25, 2023. The premature twins, conceived by in vitro fertilization, are dichorionic. People seeing the twins in person or viewing their photos online insisted they were fraternal twins (Solé, Reference Solé2024). Interestingly, their mother had evidence from genetic testing showing that the twins were identical, but few people believed it. However, as explained by a representative of the Cleveland Clinic, identical twins are not always identical in appearance. The twins’ physical discrepancies can be linked to different genetic mutations and/or unequal prenatal nutrition. It will be of interest to see whether Sophia and Adriana’s looks become more alike over time, as they follow their genetic growth curves.

References

Colapinto, J. (2013). As nature made him: The boy who was raised as a girl (2nd ed.). Harper Perennial.Google Scholar
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McBride, J. H., & Monson, T. A. (2024). The evolution of primate litter size. Humans, 4, 223238. https://doi.org/10.3390/humans4030014 CrossRefGoogle Scholar
Money, J., & Ehrhardt, A. (1973). Man & woman, boy & girl: Differentiation and dimorphism of gender identity from conception to maturity. Johns Hopkins University Press.Google Scholar
Segal, N. L. (in press). Tribute to Dr. Milton Diamond: Twin studies of transsexuality. Twin Research and Human Genetics.Google Scholar
Segal, N. L., & Montoya, Y. S. (2018). Accidental brothers: The story of twins exchanged at birth and the power of nature and nurture. St. Martin’s Press. (Spanish translation, Grupo Planeta, Barcelona, Spain).Google Scholar
Solé, E. (2024, October 17). Babies ‘Barely look like sisters’, their mom says … but they’re identical twins! Today. https://www.today.com/parents/babies/identical-twins-dont-look-alike-rcna175744?cid=eml_parents_20241018 Google Scholar
Figure 0

Figure 1. Dr H. Keith Sigmundson. Courtesy: Dr Sigmundson.