LitCharts assigns a color and icon to each theme in The Sun is Also a Star, which you can use to track the themes throughout the work.
Immigration and the American Dream
Passion vs. Reason
Interconnectedness and Destiny
Isolation vs. Connection
Summary
Analysis
Dae Hyun stands in his store, opening and closing his cash register, wondering if it's his fault that his sons are the way they are. He's told them nothing of his past because he believes it will protect them. He thinks that poverty is contagious, and he doesn't want them to hear anything about it. His sons think that money and happiness aren't related, but they also don't know what it's like to live in poverty.
Dae Hyun understands that his experiences in Korea are influencing his sons, even though his sons aren't specifically aware of the history. This shows again that one's connection to their history exists regardless of whether or not one is cognizant of it.
Active
Themes
When Dae Hyun was a teenager, his father began grooming him to one day run the family crab fishing business. The business never did well; his family only barely survived. Throughout his childhood, he knew that he'd take it over anyway. On the first day his father took him out on the boats, however, Dae Hyun hated it. It was cold, and he watched the frantic crabs clawing over each other, trying to escape. Dae Hyun thought that coming to America would've gotten rid of that memory, but it didn't. He thinks that the crabs would've done absolutely anything to escape.
The actual history of Dae Hyun's adolescence suggests that in the present, Daniel and Dae Hyun may be undergoing the same kind of shift that Dae Hyun underwent with his father, even though he never mentions how his father felt about his decision to leave Korea. This does provide some hope that Daniel will end up okay in the end, given the cyclical nature of history and how well Dae Hyun did by forging his own path.