Are Daisy's voice and manner natural to her,or is she acting?

We get the sense that Daisy's life is a charade. She acts as if her life is a series of care free adventures but the truth is otherwise. When she is alone with Nick at the end of the chapter, Daisy lets her real voice of indignation out:

Her eyes flashed around her in a defiant way, rather like Tom's, and she laughed with thrilling scorn. "Sophisticated—God, I'm sophisticated!"