I myself see the potential stat as being what they are genetically able to achieve, with the current being what they truly do achieve. This means that the bow and arrow tribe guy will have the same potential as the guy in urban society, but not the same current.
I would be inclined to agree if stats went up based on usage.. (someone who's very physical but is never intellectual would have his physical stats go up each level but his mental stats would stagnate).. but they're not... On average, all stats go up each level, regardless of use.... The only way to limit stats is to limit their potentials.
The jungle tribesman might use reasoning a lot, however he would likely be reasoning much less complicated things then the urban man. The urban man would have been taught things like skepticism, the scientific method and logic... he would have been educated on
how to reason. By definition this would increase his potential capabilities if he took advantage of them. Likewise the jungle man would have been raised around animals and nature (In), and he would be able to interact with them much more easily.
Now the Urban man could learn to live in the jungle, as could the Jungle man live in the city... however based on their upbringing they both find it very hard....
However, if they did indeed switch places, their children would not find it nearly as hard as they did....thus it's not genetic.
Now it could be argued, quite successfully, that the difficulty in learning is from professions... a fighter learning a scientist's skill, a scientist learning a fighter's skill.. however since a profession can raise 2 stats to 90... that seems to demonstrate stats are altered by education and life experince.
In any case, these are all just game mechanics trying to model an extraordinarily more complicated system. It's nearly impossible to divide our brains into skills, and mental capabilities... since very often learning skills increases those capabilities across the board.
Again I fall back to... it's GM and players call. If you want to have a clone be identical (physical or mental) for story telling purposes, go with it... who cares if it's probably inaccurate. All sorts of fun sci-fi stories have identical clones at their root. If you don't want them to be identical, don't. There's good arguments on either side, and it's balanced either way, so go with whatever way is the most fun and makes the story and game the most interesting.