Perhaps the most important lesson Antonio learns is that he will have to decide his future and his fate for himself. For much of the novel, young Antonio feels pulled between conflicting expectations.
Tony feels all of his family’s conflicting expectations weighing down upon him, and he wishes to find his own identity.
Tony, however, does not realize that it is within his power to make his own choices for himself until late in the novel. Conversations with his father and with Ultima lead Antonio to the realization that he not only has the ability to choose for himself - he has the responsibility to choose for himself as well.
Every generation, every man is a part of his past. He cannot escape it, but he may reform the old materials, make something new.
After being pressured by his father and mother to set certain goals for himself (to become a priest; to become a vaquero, etc.), Antonio comes to understand that loyalty to family is not defined by giving up one's identity to the family but in simply being there with them, caring, and trying to understand them.
This lesson of mature and empathetic interpersonal understanding is tied together with Tony's lesson regarding his expectations for himself.