Final answer:
Kent, known for his impatient and angry demeanor, is more likely to develop cardiovascular issues compared to his relaxed younger brother, due to his Type A behavior pattern that is linked to an increased risk of heart disease.
Step-by-step explanation:
Based on the provided research, Kent, who is often impatient and subject to angry outbursts, is more likely to develop cardiovascular issues. The studies mentioned, including the research by Haynes et al. and Friedman and Rosenman, indicate that a personality characterized by high levels of anger and hostility, such as a Type A behavior pattern, is associated with an increased risk of heart disease. Moreover, such dispositions can lead to confrontational social interactions that further contribute to cardiovascular strain. Therefore, compared to his more relaxed brother, Kent's disposition suggests he may be at a higher risk for cardiovascular problems.