I went to Oxford in December for interviews.
Another girl from my college who I know quite well, applied for the same subject as me, submitting the same pieces of written work as me as we're in the same classes but she had better GCSE grades than me and AS grades.
I got an interview and she didn't. There was literally nothing between us on paper.
EXCEPT...
My dad went to Oxford?
Who knows if that was the reason.
I suppose I'll never know.
But I can safely say there's no probing questions as to the social circles you move in or the education history of your family. It is purely academic grilling.
And besides, even if you have connections within a college, there are several interviews for each candidate from various tutors, surely if someone doesn't find you to be suitable to be a prospective student of theirs, they won't accept you because of who your parents are etc?
Bottom line, who knows what goes on behind those old, stone walls?