His great-grandfather on his father’s side was Gustave A. Mueller, a doctor. His great-great-grandfather, August C.E. Müller, was originally from Pomerania, Germany, according to an old article about Gustave. This region is now part of Germany and Poland. August immigrated to the United States in 1855, where he settled down in Ohio. August’s wife was also a native of the same region as her husband.