Personally, I would assume: 1) Influences + 2) History + 3) A unique perspective.

1) is all influential data, from physiology to psychology. Your native/biological brain chemistry/coding, the environmental and external influences of the conscious and subconscious mind, including culture and social interaction.

2) collected data from your past that would have a resonant effect on influence and response to newly collected data, as well as being an archive for unique perspective, and a shortcut to a definable individuality. His is anything from fear of dogs because you were bitten as a child, to social historys that influence the factors of attraction. Which is why amnesia works as a writing tool for discovering individuality. A conscious sentient being with no history, could be a copy.

3) A unique perspective. A single unit of data collection through a non replicable source, that then will be interpreted for response after being filtered through history and influence. It would be this that I find the most defining point of individuality in a world where consciousness and brain data can be replicated and uploaded.

These all affect each other and contribute to the evolution of the self. This is kind of related to Sartre's idea of Existence preceding Essence, wherein to be considered an individual, you must first exist as such. If you were to upload your data into an android, before consciousness happens there are two of you. Once one begins to receive its own perspective set of data it is an individual. It has been compared to waking up a new person everyday because of the way that our consciousness is ever evolving.

Kind of like an adhesive wall, and existence is just hurling all of the human experience it can, down the very narrow tunnel of our perceptive field, what sticks is essential what makes an individual. And it's that which I would consider a ghost.