For years, US Senator John Forbes Kerry had sought to know the true story of his immigrant grandfather, Frederick A. Kerry, the patriarch who established the family in Boston and then mysteriously took his own life. The story, it turns out, began in a small town in the Czech Republic that once was part of the Austrian empire. Birth records there show that Frederick A. Kerry was born as Fritz Kohn to Jewish parents, according to a genealogy specialist hired by the Globe. Kohn changed his name to Kerry around 1902 and emigrated to the United States in 1905, eventually...