His wife was Janet Roberton, the daughter of James Roberton, a Lord of Session (in turn a grandson of James Roberton, Lord Bedlay an ordinary Lord of Session during the Restoration.
The couple were second cousins, both descendants of Robert Bruce, Lord Broomhill.
[3] Bruce's descent was through his father Thomas Bruce 7th Earl of Kincardine and his grandfather Alexander 4th Earl of Kincardine.
His wife's mother was the daughter of Janet Bruce, Alexander's sister.
This biography of an earl in the Peerage of Scotland is a stub.