It is definitely caused by cultural acclimitazation of the personality - Vulcans have great natural abilities of both a "mind" and a "beyond mind" type, as well as strong emotional abilities. (Yes, their emotions are very strong, but so is their emotional sensitivity.)

However, these abilities also come with a great responsibility to not use them for ill purposes, which an immature Vulcan could easily do if they let their strong emotional resonance get out of control. Hence the rigid cultural strictures.

Of course, ideally, a fully-developed Vulcan society would advocate that only for the young, and would help mature members of the species to go beyond the limitations that were previously imposed upon their impressionable minds. The current Vulcan society has so far found itself unable to break the pre-conditioning, however.