Complex sentence: He is the son of a high-ranking Corps CO but he rejects any help from his family, though he is clueless that much of his fame and achievements owes at least partially to his father's influence.
Split into simpler sentences: He is the son of a high-ranking Corps CO but rejects any help from his family. However, he is clueless that much of his fame and achievements owes at least partially to his father's influence.