In the novel and in that time and place in history, your family name would establish the order of precedence in society. In the case of the Elliots, you can see how seriously Sir Walter took his pedigree. He had a heraldry book detailing the history of the family name, of the baronet, and of their lineage in detail. He had his family semi-brainwashed into living and breathing the family name, had his servants act out the family name, and had his daughters and servants hail the family name.
Elizabeth and Mary had been bitten by the bug of stretching the fantasy that the Elliots were still powerful and almighty. Anne had more common sense and refused to give in to it. But it just goes to show how your family, nee, its pedigree would determine a pre-set number of specific social behaviors that include Sir Walter's hedonism, and his daughters' snobbery.