Lord Francis Douglas Marquess of Queensberry; a younger brother, Lord Archibald Edward Douglas (1850–1938), who became a clergyman; and a younger brother and sister, the twins Lord James Douglas (d. 1891) and Lady Florence Douglas (1855–1905), who married Sir Alexander Beaumont Churchill Dixie, 11th Baronet. He was an uncle of Oscar Wilde's lover Lord Alfred Douglas, and a younger brother of John Douglas, 9th Marquess of Queensberry. In 1858, Douglas's father, Lord Queensberry, died in what was reported as a shooting accident, but his death was widely believed to have been suicide. In 1862, his mother, Lady Queensberry, converted to Roman Catholicism and
James Douglas, 3rd Lord Mordington examined). James Douglas, 3rd Lord Mordington, married Anne (b.1651) daughter of Alexander Seton, 1st Viscount of Kingston by his first wife, Jean (d. August 1651), daughter of Sir George Fletcher, of the Innerpeffer family. Their son and heir was George Douglas, 4th Lord Mordington. James Douglas, 3rd Lord Mordington James Douglas, 3rd Lord Mordington (born 1651), succeeded his father William Douglas, 2nd Lord Mordington, It is recorded in "The Great Seal of Scotland" (charter number 294) confirmed at Edinburgh on 2 August 1662, that James Douglas, Master of Mordington, eldest son of William Douglas, 2nd Lord Mordington, acquired the estates