Duncan was born on the island of Tiree (written as Tyree at that time) on 30 March 1871. He had younger siblings Mary and Angus.
On 16 January 1816 Duncan married Rachel Thomson at Ardchattan.
Their children were:
Peter Kennedy 1822
Elizabeth (Eliza) Kennedy 1831
Isabella Kennedy 1832
Duncan, Rachel and family are shown as living at Dail in the 1841, 1851 and 1861 censuses.
Duncan died on 25 June 1877 at Muckairn, Argyll.