I do take Christopher's point above on board, and must fully admit I hadn't really thought about it in those terms. Certainly I remember certain early drafts of what became the 1996 TV Movie stated outright that the Doctor got into the academy because of his aristocratic roots within the Gallifreyan heirarchy, particularly the Prydonian chapter. I don't think canonical Who ever goes quite as far as to say he's the heir to some Rassilon-given legacy, but it is a reasonable extrapolation.
If the Doctor has got aristocratic blood, enough so that gets him in with the toffs of the academy (albeit he doesn't share their superior view of the universe), then we must also assume Susan shares that lineage. If indeed she truly is his grand-daughter.
If the Doctor has got aristocratic blood, enough so that gets him in with the toffs of the academy (albeit he doesn't share their superior view of the universe), then we must also assume Susan shares that lineage. If indeed she truly is his grand-daughter.