Hobson was born on August 17, 1870, in Greensboro, Alabama, United States. He was the second son and second of seven children of James Marcellus and Sarah Croom (Pearson) Hobson, and a grandson of Richmond Mumford Pearson, chief justice of the North Carolina Supreme Court. His father, the son of a planter, was a lawyer, one-time state legislator, and for many years a probate judge.
The boy himself had at an early age some of the marks of distinction. He was "formal, " "grave faced, " precocious, and there was "a smouldering fierceness in his eyes. "