I am not sure exactly what to make of this symptom. Everyone experiences their body in slightly different ways, and it is possible that your brain has simply adapted cues from the two sides if your body in these subtle ways, such that the two sides of your body don't feel exactly the same. If the sensation has been stable since early childhood then, as you say, it is unlikely to be related to the multiple sclerosis
This is not to say that multiple sclerosis cannot produce some very strange symptoms indeed! Some of these symptoms could include all sorts of sensations like coolness, numbness
, tingling, etc in different parts of the body. Therefore, you should definitely discuss these symptoms with your neurologist
, as they could definitely be part of a multiple sclerosis pattern.