When Marcus Humphrey was born on 31 May 1784, in Bluemont, Loudoun, Virginia, United States, his father, Cpt. Thomas Marcus Humphrey Jr., was 41 and his mother, Mary Marks, was 41. He married Margaret Marks on 3 June 1809, in Loudoun, Virginia, United States. They were the parents of at least 1 son. He died on 19 November 1839, in Loudoun, Virginia, United States, at the age of 55, and was buried in Short Hill Mountain, Loudoun, Virginia, United States.