I can tell you that my best friend in grade 3 would have loved to go to America to pursue medicine. In fact, he would have loved to pursue ANY education. He dropped out IN GRADE 3 and became a SHOE-SHINER. On the street. 8 years old. He was a fast runner and had done well in school. Do you think genes will have helped him through this trauma? The kid could get into Harvard with this kind of life experience, but he won't. He was good in school, but got screwed. His family was dirt poor and his father had died. Tell this 8 year old hard-working kid that he can make it to an American MD school if he works hard enough and uses his intelligence. Ya, right. What are his chances? Not applicable.
If I look at a 100% white, homogeneous population of the same race, living in a medium-sized city with 100% middle class inhabitants and no corruption, then yes, "genetic intelligence" may play a role in determining who becomes the mayor. He will be the top achiever of the MENSA test, the sole criterion for the selection process.
Guess what? How many people get into medical school? There are over 300 million people documented in the United States. How many doctors? What is the percentage of people who make it through the system to become doctors? How many would have liked to become doctors but chose alternate pathways? The numbers are statistically significant. If you look at international high-school leavers exams, there is a reason why only top 0.1% of applicants are able to select medicine. In reality, a much higher percentage would have liked to study it. How would my childhood friend afford cram school and private lessons to enter the top 0.1% of test-takers? Do you think that he will be able to afford the elite cram schools when they charge twice the minimum monthly salary to attend? He would be lucky to get into any cram school, and would be lucky to clear the minimum % for admission into ANY university program, let alone medicine. With those circumstances, guess what? He won't be getting in, no matter how "naturally intelligent" the kid is. He will work hard all his life, for a minimum wage salary, renting in a slum.
The village kid who makes it because of his "natural" intelligence alone through self-education to a US med school is the real outlier. There are millions like him currently pouring into Europe, but at best, he will constitute 0.001% of his MD class. He would be the guy/girl who smuggled himself out of war-torn Afghanistan at age 9 and made it to America on a fake passport, passing through ridiculous insurmountable barriers that no American kid ever had to know about or had to endure. The rest of his classmates will be privileged (and I don't mean this in a bad way), lucky, and most importantly, hard-working (90%). But "natural" intelligence alone is not enough. Being smart, the kid might have made it to the Taliban or have worked for the corrupt Afghan Government, but through hard-work, and calculated risks, he/she was able to achieve beyond privilege/luck. The majority of premeds do not have this type of life story. The majority of premeds will have a Western Education and will have done well as a result of their decades being born and raised in Western society, in good families, in good neighborhoods, and with good opportunities. This isn't "natural" intelligence. It's accumulated lessons beyond genetics.
Speaking of extremely small subgroups of people, physicians are already an extremely small percentage of the population. MD/PhDs are even a smaller subgroup. In a crowded premed lecture hall, if on average 10% of the class will make it into medicine, and if on average, one person wins a sheer luck event at securing a prestigious medical research position, then by sheer luck, nearly 10% of the MD/PhD program at the medical school will consist of lucky people like him/her with prestigious medical research positions (which tend to accumulate). Repeat for privilege. Advantage accumulates and builds upon itself. This is why early earners which graduate during a recession tend to do more poorly on average, despite having same IQ.
Luckily, the majority of the class will contain hard working, disciplined, and highly educated individuals. Nobody asks for "natural" intelligence in MD applications. Instead, they assess the whole applicant, including their life story, their highs and their lows.