The Penalosa brothers - both 2 division champions. The older brother even has one leg shorter due to polio. The Galaxy brothers of Thailand. The Mayweather sisterhood - ooops, that does not count?
Marquez brothers. While Michael Spinks is the greatest single fighter out of these guys, Leon Spinks falls far behind. While there is historic value of course in being the HW champ of the world, and he was very green, he still beat a 36 year old Muhammad Ali who was already slurring his words.
haha right, I Like the marquz brothers but I choose the klitschko's, having the heaveweight division( even weak) on a lock for almost a decade while being well in their 30's deserves praise.
There´s also Jeff Mayweather (both Jeff and Roger held titles), but Mayweathers don´t compete with Spinks bros resume (both olympic champions and belt holders as well). Hattons lose to Spinks bros as well, since Matthew hasn´t won anything big. K2 - Wlad is also a olympic champion and has held multiple belts for a long time; Vitali has also been at the top a long time. And if you compare all boxing brothers resume from world title fights, then Klitschkos dominance in this poll is unquestionable.
Galaxy brothers - Khaokor - WBA bantamweight champion, 24-2-0, Khaosai -49 (43 KO)-1-0 - WBA super Flyweight champion (1984 - 1991) Penalosa Brothers - Dodie Boy - IBF light flyweight, WBA, IBF flyweight - Gerry - WBC super flyweight, WBO bantamweight champion. I think these two brothers have as much claim as any brothers you listed.
If you compare just title-fights, then Marquez brothers has 23 wins in them. Klitschkos have over 30. Others don´t come close, i think.