The interviewer generally asks why you chose to pursue a career in your field to gain insight into your motivations and interests. By understanding your reasons for pursuing your chosen profession, the interviewer can better assess your fit for the role and the company. Additionally, your answer can provide valuable information about your career goals and aspirations, which can help the interviewer determine if you have the potential to grow with Massachusetts General Hospital. Overall, the question is a common one and provides an opportunity for you to showcase your passion for your field and your alignment with the company's values and mission.