I agree that Mian P's is the smoothest translation that still retains the meaning.
Do you have one brother or two brothers"
ni you yi ge xiongdi, hai shi liange ge xiongdi?
The important difference between Chao's answer and Mian's answer is that one typically uses hai shi to mean "or" when asking a question and huo to mean "or" when making a statement. You can still use huo to ask a question if you want, but it may be less clear to the listener.
Do you like spicy food or salty food?
ni xihuan chi la de, hai shi xian de?
I can eat spicy or salty food.
wo la de huo xian de dou keyi chi.