My father has one of the last hereditary royal dukedoms, which would make him the muggle equivalent of the Sacred 28 if I understand the structure correctly. If I were a generation older, I would be much more restricted in what I could or could not do. I suppose being a woman in this structure has a few benefits. My brother has fewer choices, as he will be the Duke one day, and have to inherit the running of the Duchy.
You can tell who is the direct line in our family based on how they are addressed.
Your Highness? Royal Your Grace? Close My Lord/Lady? Nope