Our identities are linked to many aspects of our physical, psychological, and emotional selves, and physical appearance is undoubtedly one of the strongest markers of identity. How people see themselves—and how they imagine others see them—becomes an inextricable part of one’s ego and feeling of self-worth, informing how they interact with the world. When Chess, Emma, and Finn discover the existence of their doppelgängers, the Gustanos, they begin to question their own identities. As they compare their lives with the Gustanos, they desperately search for differences, hoping to distance themselves from possible collateral damage. If they live in different states, and Mr. Gustano is named Arthur as opposed to Andrew like their own father, then perhaps, they reason, their identities are not so tied together, and the entire bizarre situation can be explained away as a coincidence. In the “real” world, the world in which the Greystones grew up, their mother tried to conceal their identities to protect them, never allowing their names or pictures to be published on their school website and meticulously monitoring their online activities. In an age when identity theft can mean financial ruin, for the Greystones, identity exposure can mean life or death.

In another sense, identity can be used to one’s advantage.