Nancy L. Segal

Nancy L. Segal is professor of psychology at California State University, Fullerton, and director of the Twin Studies Center. She has authored over 250 scientific articles and six books on twins and twin development—a recent survey placed her among the top 2% of well-cited scientists worldwide. Segal's 2012 book, Born Together—Reared Apart: The Landmark Minnesota Twin Study, won the 2013 William James Book Award from the American Psychological Association. Her other books include Twin Mythconceptions: False Beliefs, Fables and Facts About Twins, Someone Else's Twin: The True Story of Babies Switched at Birth, Indivisible by Two: Lives of Extraordinary Twins, and Entwined Lives: Twins and What They Tell Us About Human Behavior. Her 2018 book Accidental Brothers follows the incredible life histories of two sets of identical male twins in Colombia who were inadvertently switched at birth.

Segal has appeared on the Today Show, CBS This Morning, Good Morning America, and The Oprah Winfrey Show, and been featured in the New York Times, Wall Street Journal, and Atlantic Monthly. She has also served as a consultant and expert witness for the media, the law, and the arts. Born in Boston and raised in New York City, she lives in Southern California.