Heinrich Hermann Robert Koch was born on December 11, 1843 in Clausthal, Hanover, the third child of Hermann Koch, a mining engineer, and his wife Mathilde Julie Henriette Biewand, daughter of an iron-mine inspector. His parents were blood relatives, Mathilde being her husband’s grandniece. They were Lutherans and natives of an old miuntain town of some 10, 000 inhabitants, situated about fifty miles south of Hannover. His father began his career as a miner but broadened his horizons as a young man by visiting several European countries. His wife bore him thirteen children. Two died in infancy, leaving Robert with six brothers and two sisters younger than himself and two elder brothers. When the boy was about ten years old, his father became overseer of all local mines and acquired the title of Bergrat.