The search for identity – where and to whom one belongs – is at the heart of Daniel Deronda. Daniel has no idea what his background is; he just knows that Sir Hugo adopted him once upon a time. He doesn't know whether Sir Hugo is his real dad, or if his parents were other English people, or if they were from another country, or, heck, if they were pirates. Daniel's desire to get to the bottom of this question informs the way he goes about his daily life, the way he develops his personal and political sympathies, and the way he interacts with others.
In Daniel Deronda, personal identity is something that someone feels from within.
In Daniel Deronda, people figure out who they are in relation to others.