You're special, but you're also nothing special. [ said with a little smile of his own. Sometimes he's halfway decent at reassuring. ]

As for your question, it's memories—cogito ergo sum and all that. I remember being the Doctor. I remember living through what other Doctors have done. And I want to be the Doctor, so I'm still the Doctor. You remember being the First Gansey, you remember living through what the First Gansey's done, you seem like you want to be Gansey, ergo you're still Gansey.