Unlike my other posts on this forum, I'm just going to just start rambling my thoughts on the issue (ie make it up as I go along) and completely reserve the right to reverse any opinions I may espouse here:
Every year 4 million children are born in the United States. Just ballparking it, using gorilla math (remember that 'make it up as I go along' bit?) I'd estimate that ~95% have the innate ability to become a physician in the US. What it takes to get said baby to medical school depends on that individual of course. There are some (~1%) that no matter what position you put them in, whether it be middle-class suburbia, upper class hamptons or inner-city ghetto, they are going to rise to the top because of who they are. They are born with the innate intelligence that simply carries them. The other 94% if put in the right circumstances could go to medical school, if they wanted. In the extremes, single-parent household, no family graduating high school, living in the inner-city, very few of that 94% could make it. Best childhood/development possible... ie. good support, but not too much, ample resources, but not spoiled, intact family etc? Ya, I really think that 95% could make it to medical school.
But, life gets in the way. These are my core:
#1 Communication skills
#2 Knowledge
#3 Drive
#4 Kindness
You need to have competency in all 3 of those. Everyone has to learn them from day 1 of pre-school on. Some people are better learners than others, but with ample experiences, I think that 95% of people can do it. Communication skills: This is everything, from how to troubleshoot things to how to call a consult to how to work in a team etc. Superior communicators do better professionally. Verbal skills on the MCAT? It matters. No, having the best vocabulary doesn't, but reading comprehension? Attention to details? Being able to organize your thoughts? Incredibly important. But, this isn't about MCAT prep, you don't improve your reading comprehension or your communication skills by studying for the MCAT. It starts with reading, writing, getting feedback and improving. Starts in elementary school and builds from there. Your environment is huge. I tell high school students that want to go to medical school that if you want to improve your chances of getting in the most, start reading. I don't care if it's fiction, biographies, the economist, whatever. Being able to read and write well is invaluable.
Knowledge: The amount of knowledge that you need to be a practicing physician is actually relatively small (in terms of years committed). The vast majority of what you use on a day to day basis was learned in medical school and beyond, NOT the preceding 17 YEARS of education. Everything before medical school is about being able to gain knowledge and proving that once you reach medical training you are going to be able to absorb it and use it. Medical school and residency are long and hard, if you don't have the ability to survive it, there is no point in going. Up for discussion, but most people think that OChem and Physics are the hardest pre-med classes. I honestly believe with adequate preparation and support, almost anyone can do well in those classes. Maybe not get an 'A', but certainly well enough for medical school. But, it starts from elementary school. How many pre-meds struggle with mathematics? How many cower at the concept of using calculus? The most poignant example for me was my medical school biostats class, where a large (5+) number of students complained because they were expected to divide 459 by 3 with a pencil and paper on their exam. They claimed that they should get calculators because in the 'real world' they would always have one. Well, how hard is Physics if you struggle with long division? I don't think that any of them are innately unable to do long division. But, they certainly in 13 years of kindergarden, elementary, middle, and high school education never actually got comfortable with dividing a three digit number by a one digit number. You can apply this to hundreds, if not thousands of other examples of basic education that is lost on many students, some because of lack of resources/teachers (inner cities) more commonly in the pre-med crowd, being spoiled/babied through their schooling and not maximizing on their education.
Drive: Some of this is innate, but a lot of it is part of how you were raised and what was going on around you. If you aren't hungry, you don't chase after more. Medicine is a long road and a lot of it is thankless, even after you get out of residency. If you don't have the personal need to push yourself, you are going to have a rough time.
Kindness: In the words of my mentor, "You have to give a ****." Medicine is unique in that virtually every job you could do after training is geared around helping other people. Yes, some are more superficial than others, but the lion's share revolve around seeing people on either the worst day of their life (or close to it) or keeping people from having the worst day of their life. Other jobs can claim this to a certain extent, but it is no where as universal. If that doesn't get you revved up and going, consider doing something else. I'm not saying don't apply to medical school. I'm saying that this is the big perk that we get and if it isn't a major motivator, there have to be a lot of other good reasons for going down this road. Like the others, sure, some people are born psychopaths, but everyone else is a product of their environment. How they were treated, how they were raised. Their valuing of human dignity and life, etc. It isn't something you learn in a classroom. It is something you learn from your parents, siblings, teachers and other mentors.
tldr: [ramble off]