This rumor likely stems from concerns about appearing to benefit from nepotism or favoritism. Admissions committees, including at Ross, are focused on evaluating each candidate on their own merit, so your professional achievements, leadership potential, goals, and fit with the program.
Mentioning that a family member is an alum/alumna or currently at Ross isn’t negative, but it’s important how you frame it. If it’s relevant to your story, for example, they inspired your interest in Ross or gave you insight into the culture, a brief mention is fine. Just avoid giving the impression that you're relying on that connection to strengthen your candidacy.
In interviews, the focus should remain on you, that is, your journey, values, and how Ross aligns with your aspirations. That’s what the admissions team wants to understand