Born Together―Reared Apart: The Landmark Minnesota Twin Study

The identical “Jim twins” were raised in separate families and met for the first time at age thirty-nine, only to discover that they both suffered tension headaches, bit their fingernails, smoked Salems, enjoyed woodworking, and vacationed on the same Florida beach.

Order on Amazon, Harvard University Press.

Accidental Brothers: The Story of Twins Exchanged at Birth and the Power of Nature and Nurture

The riveting story of two sets of twins separated at birth and improbably reunited as adults, a dream case for exploring nature vs. nurture. Accidental Brothers tells the unique story of two sets of identical Colombian twin brothers who discovered at age 25 that they were mistakenly raised as fraternal twins ― when they were not even biological brothers.

Order on Amazon, Barnes and Noble, Books-A-Million and IndieBound.

Twin Mythconceptions: False Beliefs, Fables, and Facts about Twins

Shedding new light on over 70 commonly held ideas and beliefs about the origins and development of identical and fraternal twins. Using the latest scientific findings from psychology, psychiatry, biology, and education, the book separates fact from fiction.

Order on Amazon or Elsevier.

You are Invited to BRAINS UNCORKED!!
I will speak at the Nickel Mine, 7:00 pm
FREE EVENT!! 
Los Angeles, CA, February 24, 2025
https://www.eventbrite.com/e/brains-uncorked-by-coriolis-at-the-nickel-mine-tickets-1983277707010?utm-campaign=social&utm-content=attendeeshare&utm-medium=discovery&utm-term=listing&utm-source=cp&aff=ebdsshcopyurl

Watch my recent interview with Dax Shepard in Armchair Expert!
https://www.youtube.com/watch?v=hNJTWgQnGF4

I delivered a TedX talk, Manhattan Beach
November 15, 2025, https://tedxmanhattanbeach.org/
Watch on YouTube:
https://www.youtube.com/watch?v=jIMziH5GCvQ

Watch my interview in Sri Lanka on Twins
https://www.youtube.com/live/niSkrOiLTRI?si=iDOSf4Hm-t4qv-cf

https://www.sciencedirect.com/science/article/pii/S0022096525000785
See my tribute to the late Dr. Helen E. Fisher,
Anthropologist and Identical Twin
https://authors.elsevier.com/c/1kuTF3tz49AMkJ


See the just released film, THE ACCIDENTAL TWINS,
Doc film on doubly switched Colombian twins, Netflix;
https://www.netflix.com/title/81627034?trkid=13747225&s=i&vlang=en&clip=81776819; www.netflix.com/title/81627034

Watch my Opening Address, International
Twin Congress. September 26, 2024, Assisi, Italy
https://www.youtube.com/watch?v=Gmthl0i-Bhs&t=1433s
start at about 23 minutes

See my newest article on repeat measure of IQ in two reared-apart twin samples and a sample of virtual twins (same-age unrelated siblings reared together).
https://authors.elsevier.com/sd/article/S0191-8869(24)00211-3

See my new article that describes two new parenting concepts: "Assortative Parenting and Assortative Cross-Parenting: New Views of Parental Preference for Selected Children. https://www.sciencedirect.com/science/article/pii/S0378378223001998

Listen to an April 17, 2024 NPR-1A program about twins.
https://the1a.org/segments/the-tea-on-twins/

C-SPAN-2, Book TV!  WATCH THE SHOW! Gay Fathers, Twin Sons: The Citizenship Case That Captured the World, and The Twin Children of the Holocaust: Stolen Childhood and the Will to Survive.
https://www.c-span.org/video/?530176-1/gay-fathers-twin-sons-citizenship-case-captured-worldWatch my Skeptic September 1, 2023 interview about my 2 recent books,

hosted by Michael Shermer
https://www.skeptic.com/michael-shermer-show/nancy-segal-twins-behavior-genetics-eugenics-human-behavior/

Listen to my August 17, 2023 interview on Gay Fathers, Twin Sons
with host Larry Mantle on AirTalk: start at 33:38
https://podcasts.apple.com/us/podcast/airtalk/id73329334

You can hear my 8/2023 conversation with Chris Williamson, of Modern Wisdom Podcast
https://www.youtube.com/watch?v=rRjXwdEI-lY

Please see this news article about an extraordinary July 16 event--i spoke here at the book launch of the world's oldest survivor of Mengele's Auschwitz experiments.
https://www.australianjewishnews.com/memoir-highlights-survivors-amazing-life/

Listen to my interview on NPR (AirTalk with Larry Mantle, on my new 2023 book, The Twin Children of the Holocaust: Stolen Childhood and the Will to Survive. (Scroll down to 7th segment). Lasts about 17 minuteshttps://www.kpcc.org/podcast/airtalk/people-want-to-know-what-mayor-bass-is-going-to-do-about-homelessness-heres-what-she-said-during-the-state-of-the-city-address

PROGRAMS AND PAST EVENTS

Watch and read about this fascinating story of identical twins' alleged cheating and lawsuit that followed.
CNN Evening News, December 13, 2022

November 2021 release of
Nancy Segal's 7th book:

WATCH THE HALF-HOUR BBC DOCUMENTARY on Deliberately Divided, July 23, 2022. — AIRED ON 200 TV STATIONS WORLDWIDE
https://www.bbc.com/reel/playlist/split-at-birth-twins-divided

LISTEN TO MY JUNE 30, 2022 EPISODE OF MALCOLM GLADWELL'S REViSIONIST HISTORY ON TWIN EXPERIMENTS
Listen here...

LISTEN TO A RECENT NPR RADIO INTERVIEW ABOUT TWINS AND DELIBERATELY DIVIDED
Listen here...

Nature-Nurture BBC Mini-Series (Episode 1), February 10, 2022
Watch here...

Controversy! Ethical Issues Surrounding the 1960-70s New York City Study of Twins Deliberately Adopted Apart
April 14, 2022: 9:00 am Pacific time; noon Eastern time; 4:00pm UK; 5:00pm Europe
Zoom link: To come!

Sibling Revelry, Interview with actors Kate and Oliver Hudson, March 31, 2022
Listen to an interview about Deliberately Divided and many aspects of twinship
Listen here...

The Weekend University, London, UK (virtual):
https://theweekenduniversity.com/

NPR: AirTalk with Larry Mantle, KPCC 89.3
November 10, 2021, 11:40 am PT

Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart
Rowman & Littlefield

Read a review--two-page spread--in the New York Post
December 12, 2021
Read on NY Post...

See an interview with Twins Magazine about Deliberately Divided, December 2021
Read on Twins Magazine

Watch the December 19, 2021 lecture at Weekend University
Nature or Nurture?
Watch on Google Drive

Xploration Station, Season 2, Episode 1
Human Cloning and Twins, 2021
Watch here...

I look at twins as scientific treasures. Because just by acting
naturally in different research contexts, twins tell us so much about our
human behavior and how we got that way...

Bringing together the latest, cutting-edge research, with illustrative case histories of twins and their families, preeminent twin researcher Dr. Nancy L. Segal explores ways in which twins enhance our knowledge of human behavioral and physical development.

Learn More...

Someone Else's Twin

Identical twins Delia and Begona were born thirty-seven years ago in Spain's Canary Islands. Due to chaotic conditions at the hospital or simple human error, Delia was unintentionally switched with another infant in the baby nursery.

Learn More...

Indivisible by Two

This collection of case studies, following up on Entwined Lives: Twins and What They Tell Us About Human Behavior, feeds our fascination with "the tiny twists and great puzzles behind individuals' similarities and differences."

Learn More...

Entwined Lives: Twins and What They Tell Us About Human Behavior

Students and scholars interested in the twists and bedrocks of human development will find in this volume a stimulating sampler of cutting-edge research on the topics that define Freedman's career: behavior genetics, human ethology, evolutionary psychology, and culture.

Learn More...

Coming Soon!

Twin Mythconceptions

Shedding new light on over 70 commonly held ideas and beliefs about the origins and development of identical and fraternal twins. Using the latest scientific findings from psychology, psychiatry, biology, and education, the book separates fact from fiction.

Learn More...

Born Together Reared Apart

The identical “Jim twins” were raised in separate families and met for the first time at age thirty-nine, only to discover that they both suffered tension headaches, bit their fingernails, smoked Salems, enjoyed woodworking, and vacationed on the same Florida beach.

View PDF...
Learn More...

Wall Street Journal (WSJ.com, Bookshelf) Sept 14, 2011

“Segal writes clearly and passionately, and yet she rarely strays from the precise language of a social scientist. The result is an engaging narrative intertwined with a careful attempt to draw sound conclusions from the facts... The book has much to tell us about the ways in which genes, environments and their interactions shape who we are.”
Read The Whole Review:
http://online.wsj.com/article/SB10001424053111904140604576496092267537366.html

New York Post
https://nypost.com/2011/07/24/one-of-these-kids-is-not-like-the-others/

Publishers Weekly

“Insightful . . . with a solid mix of clinical observations . . . and compassionate reflections[,] Segal assesses complex legal, moral, and ethical questions.”

John Ed Bradley, author of Tupelo Nights and Restoration

“On its face Someone Else’s Twin is a gifted researcher’s exploration of the moral and legal crises that resulted when a hospital failed at a routine task and switched twins at birth, denying them each other. But the book is also a profound and heartbreaking mystery story that confronts the issue of personal identity and provides answers to questions that have stumped us all: Who am I? Where did I come from? Where am I going?”

Preston Williams, Washington Post staff writer

“With the frequency of twinning almost doubling in the last thirty years, Segal’s thorough yet affecting work serves as a modern window into nature versus nurture and the wrenching consequences of inadvertently twisted family ties. In some cases, the black sheep of a family is not a black sheep at all, just a misplaced one.”

Nancy Stern Winters, Lookalike Productions

“As an identical twin, Someone Else’s Twin is a very personal story for me. I was struck by how Nancy Segal so poignantly portrayed the plight of twins switched at birth. It’s beyond belief to me that the closeness I’ve come to share with my twin sister might never have been possible had this kind of switch happened to us. Truly a nightmare. Segal’s attention to detail and professional and personal insight make this a fascinating read.”

Kimberley Weatherall, Chair, International Council of Multiple Birth Organizations (ICOMBO); acting executive director, Multiple Births Canada (MBC)

“Nancy Segal introduces the reader to a thought-provoking examination of who we are as individuals, demonstrating how easily that can all change through the carelessness of another. As a parent of monozygotic twins, and as a volunteer dedicated to improving the lives of multiple-birth individuals and their families, it is heartbreaking and overwhelmingly sad to see the long-term impact a mistake at birth can have on the lives and relationships of everyone involved.”

Kirkus Reviews

SOMEONE ELSE’S TWIN: The True Stories of Babies Switched at Birth

“Noted twin-study expert Segal (Psychology/California State Univ., Fullerton; Indivisible by Two, 2007, etc.) doubles the fascination with switched-at-birth twin research. An expert glimpse into the many-faceted world of genetics, family culture and identity.”
Download the review...

Library Journal

SOMEONE ELSE’S TWIN: The True Stories of Babies Switched at Birth

“Twin studies have proven to be a valuable tool for assessing the influence of genetic factors on individual traits and behavior. Here, however, Segal (psychology, California State Univ.; Entwined Lives: Twins and What They Tell Us About Human Behavior), who has an extensive research background in twin studies (and is a twin herself), provides a novel twist on the traditional nature vs. nurture debate.”
Download the review...