his grandfather alfred edwin brain, sr. (4 february 1860 – 25 october 1925) was considered one of the top horn soloists of his time, while his uncle alfred edwin brain jr. (24 october 1885 – 29 march 1966) had a successful career playing horn in the united states with the new york symphony society and later as a soloist in hollywood. brain's father aubrey (12 july 1893 – 21 september 1955) was a teacher and held the principal horn position in the bbc symphony orchestra, producing the first mozart horn concerto recording in 1927. brain's mother marion brain was also a composer and wrote cadenzas to the first and third mozart horn concerti which her husband then performed. the family tradition also extended to his brother leonard brain (1915–1975), an oboist who performed with dennis in a wind quintet that dennis formed. tina brain, one of leonard's children, also became a professional horn player.