Can wannabes actually be what they want to be?

Could Germans who are fascinated with American Indian culture, and even speak a tribal language, ever actually be Indians? A quick answer may be a faulty one. How about white kids trying to be black? Is their desire "to be black" superficial and facilitated by the knowledge that they can retreat to being white at the slightest discomfort? I once heard a white Nun speak who had devoted her entire adult life to helping black kids. She was clearly identified with those kids and seemed in sync with black culture. Is it likely that she was accepted as part of the black community? Do people in culturally/racially mixed marriages fully partake of each other's culture? These are tough questions with no easy answers. What do you think? Pro and con examples would be welcomed.