Final answer:
It is not mentioned in the given information who Sergio was angry at when he heard his Nana talk rudely to his father. Therefore, we cannot determine who Sergio was angry at when he heard his Nana talk rudely to his father, Paul Kinkaid.
Step-by-step explanation:
In the given information, there is no mention of a character named Sergio or his Nana.
It is not mentioned in the given information who Sergio was angry at when he heard his Nana talk rudely to his father.
Therefore, we cannot determine who Sergio was angry at when he heard his Nana talk rudely to his father, Paul Kinkaid.