Nancy Segal (Deliberately Divided: Inside the Controversial Study of Twins and Triplets Adopted Apart) is an evolutionary psychologist, behavioral geneticist, and author. Nancy joins the Armchair Expert to discuss whether there’s anything predictable about a twin who comes out first, why in twin studies differences are not deficits, and her work with the Minnesota Study of Twins Reared Apart. Nancy and Dax talk about the unexpected reason identical twins are more alike that any other pair of people, the concept of inclusive fitness to explain differential genetic behavior, and why doppelgängers can be an effective test for criticism of twin research. Nancy explains her argument that twins fundamentally challenge how we think the world works, the remarkable fact that children born on the same day to two sets of identical twins are genetic fraternal twins, and why only identical twins raised apart are able to see themselves in a life unlived. Watch Armchair Expert episodes: https://www.youtube.com/playlist?list=PLzPEuwClyOzDdlrAmU-IwKncG87qrF7Vw Follow Armchair Expert on social: https://www.instagram.com/armchairexppod https://www.facebook.com/ArmchairExpPod/ https://twitter.com/armchairexppod Connect with Wondery https://wondery.com/shows/armchair-expert-with-dax-shepard/ https://www.facebook.com/WonderyMedia https://twitter.com/WonderyMedia https://www.instagram.com/WonderyMedia https://www.tiktok.com/@wonderymedia About the Show: Hi, I’m Dax Shepard, and I love talking to people. I am endlessly fascinated by the messiness of being human, and I find people who are vulnerable and honest about their struggles and shortcomings to be incredibly sexy. I invite you to join me as I explore other people’s stories. We will celebrate, above all, the challenges and setbacks that ultimately lead to growth and betterment. What qualifies me for such an endeavor? More than a decade of sobriety, a degree in Anthropology and four years of improv training. I will attempt to discover human “truths” without any laboratory work, clinical trials or data collection. I will be, in the great tradition of 16th-century scientists, an Armchair Expert. Watch Armchair Expert every MONDAY, WEDNESDAY, and FRIDAY here on Youtube! Listen to episodes ad-free by joining Wondery+ in the Wondery App, Apple Podcasts or Spotify. Start your free trial by visiting https://wondery.com/shows/armchair-expert-with-dax-shepard/ Chapters: 0:00 – Intro 1:22 – Interview with Nancy Segal 1:16:36 – Fact Check #armchairexpert #daxshepard #nancysegal #twins