I artikeln i Memory Alpha på Vulcans har Vulcan-hjärnan förmågan att fysiskt modifiera sig:
Unlike most humanoid species, traumatic memories were not only psychologically disturbing to Vulcans, but had physical consequences as well. The Vulcan brain, in reordering neural pathways, could literally lobotomize itself. (VOY: "Flashback")
Vulcans learned to gain conscious control of many of these functions, allowing them to regulate their bodies to a high degree by simple will power. When injured a Vulcan could go into a trance-like state, using this ability to concentrate all of his or her energy onto repairing the injury. (TOS: "A Private Little War")
Att veta att det här är lite extra information från sidan på Emotions :
Since Vulcans have the capability to exert a level of conscious control over virtually all of their body functions, they can actually manipulate the neural pathways that regulate and receive the balances of neurochemicals involved in emotion. This enables them to inhibit their brain from forming the neural impulses that create conscious emotional mental states, thereby actually suppressing their innate emotions. The psycho-suppression system in the Vulcan brain that endows Vulcans with this ability is located in the mesiofrontal cortex. (VOY: "Meld") The Vulcan ritual, known as the kolinahr, is designed to purge all remaining emotions in a Vulcan. (Star Trek: The Motion Picture)
Så nej, Vulcan förmågan att kontrollera känslor är inte dikterad genom deras genetik, men det är stöds av deras genetik. Detta visas i VOY 3x14, Alter Ego , när Tuvok gör vissa framsteg när det gäller att lära Harry Kim att kontrollera sina känslor.