Carl Wilhelm Christian Hahn was born in Weingartsgreuth, Upper Franconia, as the first son of Johann Michael Hahn (1734–1824), who was court and palace gardener on the estate of Baron von Seckendorff, later palace gardener for Count Friedrich von Pückler. He obeyed the general call to arms as early as 1813, and served as a quartermaster, and in 1816, received his honourable discharge. Afterwards, he lived with his parents in Fürth, and according to Hahn, made up his mind to devote his life to his predilection for natural history, an interest he had possessed since early childhood and which intensified during his studies in Erlangen. He commenced work on his first ornithological work, "Birds from Asia, Africa, America and New Holland". When his "often promised and well earned position" failed to materialize, Hahn undertook what was for that time, in his field, a very unusual step and went freelance. From then on, he called himself a natural historian and occasionally also a scholar. On 24 February 1820, having in the meantime qualified as a Dr. Phil. at the University of Erlangen, he married Victoria Francisca Kaltdorff, née Schaefer. His wife, the widow of a doctor of medicine, was about five years older than he, and had three children by her previous marriage. She was at this time without means, but was expecting quite large inheritance from her maternal uncle before long. Their own child, Anna Friedericke, was born at the end of 1820 or 1821.