There’s a grand tradition in non-profits of identifying too strongly with one particular person, usually the founder (and in this case family, as sometimes happens as well). After a while everyone involved (including the people charged with oversight) forgets that it’s not a personal fiefdom. See this happen all the time, and I think it’s a natural consequence of the sorts of endeavors that rely on charismatic fundraising. Even if a board is aware that the boss is using it as a vehicle for their own ends, it’s a rare board that will suggest retirement to a successful fundraiser.
Just because you (or your parents) founded something, just because you poured decades of your life into making it succeed, you still do not own it, if it’s a non-profit. A lot of people don’t understand this. Heck too many donors talk about how much they love this person or that and will donate because of the work of that person, not because of the institution they are a part of. It’s a corrosive mentality.