My medical students and residents are a pretty smart bunch. They are from several different countries, and from all parts of the U.S. Many grew up in families of modest means, and their parents have diverse educational backgrounds. One fact that unites them is the group they have been with for the ten to twenty years: their peers have had the intellectual and economic resources to get into medical school. By the time they enter their residencies, they have been surrounded by (generally) smart, academically successful, socially able young people.
When confronted for the first time by patients, the true diversity of humanity can come as a real shock. Many patients have no idea what diabetes is or what the real risks of hypertension are. They don't know what "Sig: 1 tab p.o. BID" means. Nor should they. Medical jargon is very useful, but it can be a significant barrier to patient care if the physician forgets that the patient did not spend the last eight years learning the lingo.
Being a physician means being an educator. It means gauging the knowledge level of your patient and communicating essential information in a way the patient can understand and use. It may mean calling something a "tube" or a "gland" instead of using a more technically correct word. The smartest doctor in the world is useless unless he or she can give a patient information they can use.