One of the key ways that identity is presented in this incredible novel is through Antonio's conflict between choosing the future that his mother and father both want for him. Note how Ultima summarises the differences between Antonio's father's family and his mother's family in Chapter Four:
It is the blood of the Lunas to be quiet, for only a quiet man can learn the secrets of the earth that are necessary for planting--They are quiet like the moon--And it is the blood of the Marez to be wild, like the ocean from which they take their name, and the spaces of the llano that have become their home.
Antonio feels the pressure of having to make a very tough decision between these two family backgrounds, as he faces the expectation of his parents that he will follow their particular "blood." Notice how Antonio responds to this description of the differences between his father and mother's "blood":
Now we have come to live near the river, and yet near the llano. I love them both, and yet I am of neither. I wonder which life I will choose?
It is hard not to sympathise with Antonio in his dilemma. Notice how the location of where he lives mimics the conflict going on within him as he feels pressurised to choose either the river or the llano, or to follow the Luna family "blood" or the Marez family tradition. Antonio feels he has to choose one and reject the other to form his own identity, and the decision weighs heavily upon him.