Yes and in nature they would, if they came upon each other. If your asking we we, as their caretakers, should try to get them made into a breeding pair that's more an open answer. First for some humans, we have this "yuck" factor thinking of any siblings having offspring, let alone sex. As far as breeding goes, it would most likely be okay to do. However, not something you would want to continue to do over and over again within the same group of family members. ...darn laptop is out of power...