Duncan, born in 1894, was the son of Finlay MacKinnon and Mary MacLeod of Quay. In 1900 his father, who had been grieve on Borve Farm, obtained one of the new crofts in Borve, croft 1, to which the family moved. Duncan started attending Berneray School in April 1901.

By 1911 Duncan and his older brother Hector were working as farm servants for Mrs Jessie MacLennan (née MacKenzie) at 8 Ruisgarry (Baile). During the Great War he served with the Royal Naval Reserves as a deckhand on HM Trawler Corona. On 23rd March 1916, just eleven days after his 22nd birthday, it struck a mine. Duncan was killed.