Pariah Gene

The Pariah Gene is an aberrant mutation of the human genetic code, which results in the existence of being colloquially known ans "Blanks" (for those lightly affected) and "Pariahs" (for those where the mutant gene is dominant. These Abhumans have little to no existence in the Warp, and radiates a sense of unnaturalness and unease that is unerving to other living creatures and can be painful or even lethal to psychically sensitive beings. The Pariah Gene is either passed on naturally through reproduction, but also occurs through random mutation, just like the Psyker genes. The Paria Gene is however infinitely rarer than the Psyker genes; and Blanks and Pariahs make up an infinitesimal proportion of the population (with estimations of a half dozen beings in the whole population of a medium-sized planet). Most affected die young as the palpable aura of revulsion that surrounds them makes them reviled, outcasts, or killed outright as monsters.

The Magos Biologis of the Adeptus Mechanicus have started whispering theories amongst the highest echelons of the Imperium that the Pariah Gene was willfully imparted to humanity by the C'tan to starve off Chaos after analyzing the blasphemous union of living matter and metal that is a Necron Pariah Warrior.

Blanks
Blanks, also called "Untouchables" are those humans who possess the Pariah Gene, but is not dominant in their genetic code. A Blank is often not aware of his powers and may not be able to control them, but the aura they project is highly disruptive to Psychic Powers, and a Psyker will find it difficult to impossible to affect the Blank and anyone in his general vicinity with his powers. Blanks have a better chance than true Pariahs to live a peaceful life, for since their aura of 'otherness' is rather weak, baseline humans may simply pass it off as queerness and leave the Blank alone.

Blanks are often recruited as living shields against psychic attacks by Inquisitors and forced to tag along wherever the Inquisitor goes. Generous (or pragmatic) Inquistors might even provide the Pariah with combat training and some equipment.

Pariahs
Pariahs, also known as "Blacksouls", "Psychic nulls" or "Soulless" are those abhumans where the Pariah Gene is truly dominant. The have no presence whatsoever in the Warp. Their aura of 'strangeness' is so powerful that a baseline human finds it impossible to be in the Pariah's presence, and they are a living embodiment of the worst possible nightmare to any psychically gifted being. Unlike Blanks, Pariahs can siphon and thrive on the psychic energy of Psykers, and their aura quickly proves fatal to them. Pariahs are quite often killed at birth as mutants, for their 'otherness' is very palpable.

Surprisingly, Pariahs have always been much sought after by the Imperium, first organized in the all-female Sisters of Silence order, and now trained to become the much feared Culexus Assassins.

Notable Blanks

 * Ferik Jurgen - An Imperial Guardsman of the 597th Valhallan Guard Regiment, and aide to Commissar Ciaphas Cain. Jurgen saved the life of his Commissar on more than one occasion thanks to his unknown ability to dampen psychical powers.
 * The Distaff - A group of Blanks gathered by Inquisitor Gregor Eisenhorn of the Ordo Xenos. Their leader, Alizebeth Bequin, became the Inquistors confidante and aide, and the whole group assisted Eisenhorn in many endeavours until their eventual destruction.

Notable Pariahs

 * Culexus Assassins - All Culexus Assassins are full-fledged Pariahs, trained and equipped to the highest Imperial standard to become the bane of Psykers around the Galaxy.
 * Necron Pariah Warriors - The Necron harvest Pariahs and transform them into these abominations to protect themselves from psychic activities.
 * Black Pariah - The strongest Pariah ever encountered, this Pariah only know by his codename "Spear" was trained by Warmaster Horus to assassinate the Emperor of Mankind