Robert Blaine was the son of Col. Ephraim Blaine (1741-1804) and Rebecca Galbraith (1742-1795), and the husband of Susan Metzger (1772-1853). Robert and Susan were the parents of six children, among them Rebecca Blaine, who married Rev. Jeremiah Chamberlain in Carlisle, PA, in 1818. Robert was a slave owner and served as a trustee of Dickinson College from 1811 until his death in 1826. For many years after his father's death, Robert pressed the latter's outstanding claims for reimbursement by the U.S. Congress for expenses incurred during his Revolutionary War tenure as commisary general.