I don't know that I agree that it's innate so much as it's a rare skill because not everyone learns it.
I think most people would agree that the science sections are either about memorization or problem solving. If you're premed, these are things you have finally honed- simply because you've had to. Hopefully, by the time you're ready to take the MCAT, you've taken the classes, you've taken MANY science classes for that matter, and depending on how good your undergrad is about teaching you problem solving skills, you are either good or great at it. After all, most pre-meds are science majors. These should be skills you're familiar with, and at that point all you really have to do is study.
However, to say that anyone can study and do well on the sciences doesn't seem true to me. Not everyone is "good at science", meaning not everyone has learned the skill of reading a detailed science textbook, drawing out the data seamlessly, understanding the problem at hand and coming up with a solution. It's just that pre-med sciences usually control (or they're supposed to, anyway) for those types.
Verbal is yet another skill. It requires a global understanding of a passage, it's a much more abstract way to read and interpret without getting bogged down by unnecessary details. Not everyone can do it- not cause not everyone is born with it, but because not all pre-meds learn it. And just like "problem-solving", the skill itself is hard to teach in the duration of a normal MCAT study session. It's built up through experience and teaching- a teaching that is not often done in pre-med curricula, especially if the students have always "stuck with what they're good at" and focused their attention on the sciences, without branching out to the humanities.
Anyways, my 2 cents.