The Carter Sisters (later The Carter Family).
I think the King Family Singers and the Von Trapp Family singers might maybe have some relatives in them.
In general, if we look at vocal combos, there are going to be a lot with relatives, since the voices tend to blend so well. A number have already been mentioned… then there are the Louvin Brothers, the Andrews Sisters, the Lennon Sisters, the Pointer Sisters, etc.
Yay! I get to mention the Wright brothers from NOMEANSNO.
The Proclaimers, best known for “I’m Gonna Be (500 Miles),” are a pair of identical twins.
**The Avett Brothers **include brothers Seth & Scott Avett
Barenaked Ladies, for their first two albums, included brothers Jim and Andy Creeggan - though Andy left the band after recording “Maybe You Should Drive.”
Uhhh…does Pat Benatar count?
She started touring while married to Dennis Benatar, but eventually divorced him and married her guitarist, Neil Geraldo, three years later.
Hardline started out with the Gioeli brothers, but one of them has since left.
As for Fleetwood Mac, Stevie Nicks and Lindsey Buckingham were married but split up (they were all breaking up during the production of Rumours).
[None of the Doobie brothers were each others’ brothers]
–G!
You don’ know me
but I’m your brother…
…–Michael MacDonald (Doobie Brothers)
…Takin’ it to the Streets
…Takin’ it to the Streets