The TLC show focuses on finding particular ancestors of interest for American celebrities. The episode Clark was in premiered on March 15.
Clark assisted with an episode that primarily took place in Germany. He was flown to Stuttgart, Germany, for the segment. It was filmed in a church in Bietigheim where Groban’s eight times great-grandfather, Johann Jacob Zimmermann, served as a deacon.
Clark has studied religious fanaticism and radical pietism for decades and did his doctorate dissertation on the topic. As far as experts in that field, Clark says it’s a pretty exclusive group.
“We are a small group of 17th-century scholars and we know each other well. It’s a tight-knit group,” he says.
Clark helped explain to Groban the culture of the time by going through original documentation gathered by the show’s producers. One such document was a book Zimmerman wrote under a pen name. As an astronomer and mathematician, as well as a musician and church leader, Zimmerman believed that church would end. Once it was discovered that Zimmerman wrote the book, his message was not well-received by church leaders.
“(Groban) thought his grandpa was this standup guy and I got to break it to him why he was pushed out of the church,” Clark says.
Clark’s part of the program took a day to film. He says the number of original documents the team found was impressive and the process of unfolding the information was fun.
“Josh was a really nice guy, and he has a good sense of humor,” Clark says, “This was the first time he’d seen these documents and my job was to facilitate his discovery.”