Are we all retarded?

I heard a story today from a doctor about a 27 year old patient who, because of a physical problem early in life, has the mental capacity and skills of a first grader. I wondered how it was that this patient couldn't progress beyond that level of understanding and action. How many years can you act like a first grader before you finally grasp the concepts and skills that make you a second grader? Somehow, this patient couldn't. The body can apparently be such a barrier that it can prevent progress beyond a certain point.

The theological implications of this are interesting. If I, from my vantage point, see the limits on this 27 year old patient compared to the potential of other humans, what does God perceive with respect to his mortal children and their eternal potential? Given the seemingly unbreakable boundaries of comprehension and action imposed on a mortal body, what does that tell us about the resurrection? Are all mortals just limited at different points in progression? If bodies are going to be of different types in the resurrection, what does that have to say about our eternal progression? [If you followed the link in that previous sentence, how does the word glory play into this argument?]

I have been wondering about the possibility of someone being assigned to the Telestial Kingdom. Would they be happy there? Would they ever be able to progress out of that place as they learned more? Elder McConkie emphatically stated that they would not. The logic of this post seems to support that argument.