As they say, when someone is popular, controversies arise. If a person becomes the focal point of everyone's vision, even a "Saint" would not escape having some faults pointed out. If some ill-intentioned individuals add fuel to the fire, magnifying these "blemishes" infinitely, ballooning them through endless speculation, it becomes public scrutiny. This is most detrimental to artists, which is why most of them avoid being overly high-profile, so as not to become the "shooting target" with their head sticking out.
The issue of one's family origin often appears in interviews with artists, but it's not considered an important secret. After all, everyone has parents, and some artists are even known for harmonious family relationships. So in interviews, this isn't considered a sharp issue. Ghost's question, although somewhat offensive, wasn't especially probing or difficult, so none of the staff present felt it was inappropriate.
