I.Q. is a highly overrated concept. I have proven that for myself, i.e., to my own satisfaction. Maybe someday I'll tell you about it.
The most important key to thinking/learning is thought representation modality. I have done many tests of that idea on students and am certain that their success in a given subject is governed by the means by which they represent thought to themselves. If they are taught the proper modality (which I have done for chemistry students) they suddenly learn the subject easily. If they do not initially represent thought properly for chemistry, and do not learn how, they usually either fail or simply do poorly and eventually gravitate toward something that fits their more favored thought modalities.