Tayo’s mom is Native American and his dad is white, two ethnicities which seem to conflict with one another. After Tayo returned from World War Two, army doctors diagnosed him with “battle fatigue,” and one army doctor tells his family, “No Indian medicine.” However, Tayo counters the doctor’s orders and visits a medicine man.
The choice to see a medicine man connects to his biracial identity. The medicine man is rooted in Pueblo culture, and the option to seek out this form of healing likely wouldn’t have been available to Tayo if he was only white. Tayo’s white side could be symbolized by the army doctor. The doctor’s injunction against “Indian medicine” might represent white society's attempt to suppress or control Indigenous bodies.
However, what changes Tayo’s circumstances isn’t white medicine but Indigenous traditions. It’s not through Western treatment that Tayo acquires harmony, it’s through the completion of the mystical “ceremony.” By retrieving Josiah’s cattle and commingling with Ts’eh, Tayo puts himself on the path to finding peace in his life.
However, Tayo’s whiteness isn't fully sidelined. To finish the ceremony, Tayo has to go to the mine shaft. The mine shaft, and the violence that happens there, indicate that Tayo cannot completely change his circumstances until he reconciles the destructive elements of his white side with the healing properties of his Indigenous side.
As for why Leslie Marmon Silko chose for Tayo to be half white, half Native American, think about how his dual identity could be seen as a metaphor or an emblem for the overall Indigenous situation in the United States. Even if a specific Indigenous person isn’t part white, it’s possible to argue that they still somehow have to confront the personal impact that whiteness has had on them and their culture.