Nancy L. Segal (born 1951) is an American evolutionary psychologist and behavioral geneticist, specializing in the study of twins. She is the Professor of Developmental Psychology and Director of the Twin Studies Center, at California State University, Fullerton. Segal was a recipient of the 2005 James Shields Award for Lifetime Contributions to Twin Research from the Behavior Genetics Association and International Society for Twin Studies. Source: Wikipedia (en)