Charles Park's parents saw a fifth of their fellow Koreans die in the Korean War. Adey Wassink grew up surrounded by Holocaust survivors. They've discovered that such massive trauma affects how a whole generation can process emotions or pain, which then passes on the trauma to their children and even their children's children in ways that can feel crazy-making. But this isn't just about Koreans and Jews. How do one generation's traumas change everything for the next?