Are your genes your destiny? Despite famous studies of identical twins that seem to answer in the affirmative, mathematician David Bessis says: Not so fast. He and EconTalk's Russ Roberts take a deep dive into the "twins reared apart" literature, showing how multiple flaws in those studies undercut their claims about heritability. Bessis demonstrates why the natural experiments are never perfect, and why differences across people in a particular time and place are no guarantee of what will happen to any one human being. They also discuss psychologist Eric Turkheimer's three laws of behavior genetics, emphasizing the role of unique experiences in shaping who we become.