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.

New book will be released April, 2018.

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

For media inquiries relating to Accidental Brothers, please contact Katie Bassel @ This email address is being protected from spambots. You need JavaScript enabled to view it. or 646.307.5563.

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.

Recent/Upcoming Events

Skeptics Society, Science Salon, September 17, 2017. Watch on Facebook


TedX, Manhattan Beach, Manhattan Beach, CA, November 4, 2017. http://tedxmanhattanbeach.com


International Twin Congress, Madrid, Spain, November 16-18, 2017. http://www.mcascientificevents.eu/twins2017/


OLLI, UC Irvine, February 12, 2018. https://ce.uci.edu/olli/courses/index.aspx


Literary Orange, Newport Beach, CA, April 7, 2018. http://literaryorange.org

NY Times Sunday Review

“Does Breast Milk Have a Sex Bias?”
by Nancy Segal et al.
New York Times (Sunday Review), January 21, 2017


“The Closest of Strangers”
by Nancy Segal
New York Times (Sunday Review), May 25, 2014


“The Whites of Our Eyes”
by Nancy Segal et al.
New York Times (Sunday Review), July 17, 2015

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...

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.

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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."

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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.

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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.

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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.

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