Dewitt Clinton Giddings was born July 18, 1827, in Susquehanna County, Pennsylvania. He was the youngest of eight children of James and Lucy (Demming) Giddings. Giddings worked teaching school part-time to finance his education as a civil engineer and later was employed as a railroad engineer. He began his legal studies in Honesdale, Pennsylvania in 1850. When word reached home that Giddings older brother, Giles, died of wounds received at the battle of San Jacinto, another brother, Jabez Demming Giddings traveled to Texas to Claim Gile's land bounty. Giddings, joined his brother in Brenham, Texas in 1852 and in 1853 was admitted to the Texas bar. He was his brother's junior partner in a law practice in Brenham.
In addition to his brother, Jabez Demming (J.D.), other of Giddings' brothers relocated from Pennsylvania to Texas. George Giddings and John James (J.J.) Giddings were successful operators of the San Antonio, Texas to Santa Fe, New Mexico Mail Line.