Having lived with these people all her life, Elizabeth is naturally somewhat predisposed in their favor. However, this bias does her harm. Her mother's pressure, her father's indifference, and Lydia's frivolity and brazenness are all factors that lower Elizabeth's status because she is associated with these people. Darcy notices this early on in the novel, as we see in his statement, "You cannot have been always at Longbourn" (Austin, 153). However, Elizabeth lacks Darcy's objectivity because of her having been always at Longbourn, and she fails to notice that her family is bringing her down until after reading Darcy's letter. Once she reads the letter, Elizabeth is able to see things as an unbiased observer. She compares the family situation of Darcy and Wickham, two completely different characters, to her own situation regarding herself and her family. This comparison allows her to see that the two cases are somewhat parallel. Wickham was associated with Darcy as near family, and as a result, Darcy was devalued. However, Wickham rids himself of Darcy, thus restoring Darcy's status. Elizabeth realizes that the family association between herself and her parents and Lydia is bringing her down. She discovers her partiality towards her family and that is a negative thing, and that it is bringing her down. Thus, her prejudice towards her family is reversed, and Elizabeth distances herself from her family and elevates her status. .
Interestingly enough, the converse of this family predisposition occurs between Elizabeth and Darcy. At first, she is biased against Darcy, but after the letter, the discrimination overturns itself, and she becomes his family, associating herself more with the uplifting Darcy and less with her degrading family. Before Elizabeth receives Darcy's letter, she is terribly biased against Darcy. She dislikes him mainly because of her first impression of him at the Netherfield ball, where she presumes that he is incredibly hubristic.