Charles S Peirce was the son of Benjamin Peirce and Sarah Hunt Mills, the daughter of Senator Elijah Hunt Mills. We note that this surname is pronounced "Purse". Charles was the second of his parents five children. His older brother was James Mills Peirce who became a mathematician in the Mathematics Department at Harvard, and then from 1890 to 1895 served as Dean of the Graduate School at Harvard and, after that, as Dean of the Faculty of Arts and Sciences. Charles' two younger brothers also enjoyed successful careers, Benjamin Mills Peirce as a mining engineer and Herbert Henry Davis Peirce as a diplomat.