The Baby Boomers (those born 1946-1965) are associated with the music of Elvis (b. 1935) the Beatles (Paul ’42; John ’40) Grace Slick (’39) Dylan (’41) Chuck Berry (’26) Hendrix (’42) The Mamas and The Papas (John Philips ’35) The Beach Boys (Brian Wilson ’42) etc. But when we stop looking at the music they listened to and consider the music they made, we get Black Sabbath (Ozzy and Tony Iommi ’48) Ice-T and Chuck D (’58 and ’60) The Sex Pistols (Sid Vicious ’57 Johnny Rotten ’56) Led Zeppelin (Plant and Bonham ’48 , Jones ’46 – though not Page ’44) etc. So what the Baby Boomers listened to was one thing – when they had to express themselves, we got Heavy Metal, Punk, and Gangsta Rap.
[UPDATE: The point of this post is just what the title says: to point an ambiguity in the sense of what "the music of a generation" means. This is why I picked styles not usually associated with Boomers, even though the boomers invented the styles. The point is not to draw some function machine like "Elvis in, Megadeth out", which should have been obvious since I didn't even try to give en exhaustive list the number of styles that the Boomers themselves came up with.]