Pip is ashamed of his poor upbringing. This relates to the themes of searching for identity and class struggles. Pip has to decide over the course of the novel who he wants to be—a gentleman who focuses on image, or a humble man who focuses on family.
Pip is ashamed of himself and his family once he begins visiting Estella. Before that, it never occurs to him to be embarrassed.
I had never thought of being ashamed of my hands before; but I began to consider them a very indifferent pair. Her contempt for me was so strong, that it became infectious, and I caught it. (ch 8,enotes etext p. 42)
First, Pip is ashamed of himself when Estella calls him coarse. She makes fun of his hands and his boots, and his card-playing skills. This is the beginning of Pip’s transformation into a self-centered, shallow person. He realizes that he is ashamed of Joe.
IT IS A most miserable thing to feel ashamed of home. There may be black ingratitude in the thing, and the punishment may be retributive and well deserved; but, that it is a miserable thing, I can testify. (ch 14, p. 75)
Pip describes himself as ungracious, but it is more of a reflection looking back. He feels bad about being ashamed of Joe and his humble family.
When Pip looks back and how his life turns out, he associates the shame of his family with Estella and Miss Havisham, and becomes ashamed of being ashamed.
Truly it was impossible to dissociate her presence from all those wretched hankerings after money and gentility that had disturbed my boyhood—from all those ill regulated aspirations that had first made me ashamed of home and Joe. (p. 161)
By the end of the story, after his experiences with Magwitch’s return and Miss Havisham’s death, Pip is no longer ashamed of his family. Instead, he is ashamed of himself. He sees more value in being humble and caring about his family than his status and what others think of him. He is ready to return to his roots, lower class as they may be. He has matured and grown up.