@genius32 must admit this one is all about attitude. I'm personally prejudiced against business with family, but I acknowledge in the Asian community it's the model that works; and works fabulously. Then internationally I've seen brother combinations in media - Wachovsky brothers, Nolan brothers, Miramax, Mudorchs etc etc.
A byproduct of family chamas is they tie bonds, and empower families. So I belong to 2 family chamas [paternal, maternal] by default. My conclusion it can work - they'll have their challenges but these things are only about commitment.