Editing Gene-seed (section)

===Minor Mutations===
These chapters may have cosmetic or easily-fixed mutations.

==== Emperor's Children (III Legion) ====
{{Main|Emperor's Children}}
* Implicitly defective and/or enhanced Lyman's Ear, and possibly Occulobe and Neuroglottis.
** An accident (non Chaos or other enemy action related) during the early days of the raising the Legions resulted in only two hundred Space Marines of the III Legion by the time the Emperor found [[Fulgrim]] and Chemos, forcing the Emperor's Children to work alongside the [[Black Legion|Luna Wolves]] for the early decades of the [[Great Crusade]]; due to Fulgrim's high standards of perfection being passed on the Legion's [[Apothecary|apothecaries]], Emperor's Children Aspirants had to be nothing less than physically perfect, resulting a largely stable gene-seed, including forbidding psykers to join the ranks. By the 41st millennium, however, the Emperor's Children's gene-seed is fucked up beyond all reason. Millennia of drugs from both inside and outside the Warp have damaged it greatly. While the relatively few sane [[tech-priests]] left and [[Dark Mechanicus]] working with them can and do make new Marines (thus proving their Marines can and do make new gene-seed), the chemical and other material abuse render each generation even crazier. Even before the Heresy, they were more sensitive to external stimuli, like sound, implying a defective Lyman's Ear with reduced ability to filter out sounds the Marine doesn't want to hear, and potentially similarly defective Occulobe and Neuroglottis.
*Initial batches of gene-seed were defective, carrying an infectious a super-cancer/progeria creatively called "The Blight" it also caused the entire legion's gene-seed stock on Terra to rot into useless sludge. Thankfully after Fulgrim's return the rotten batches were discontinued and replaced with fresh clean gene-seed preventing it from becoming a permanent feature of the legion. The Blight may be more of a [[Nurgle|spiritual]] infection because even after dying and having his soul swapped into new bodies Fabius Bile still suffers from all the symptoms.

==== Iron Warriors (IV Legion) ====
{{Main|Iron Warriors}}
* Implicitly defective Ossmodula
* Implicitly enhanced Progenoids:
** They have the lowest gene-seed rejection rate, which enables them to replenish their huge number of casualties with an even higher number of recruits.
** Minor Ossmodula mutation ''sometimes'' causes limbs to twist and deform as the marine grows really old (we're talking hundreds of years to millennia) - this is usually dealt with by replacing limbs with bionics, or cutting them off and placing the cripple into a Dreadnought, Helbrute, or some weird custom made dreadnought-esque walker, since due to their specialty and organization only high-ranking officers can survive for so long, and they surely ain't going to suffer from the "Crazed" rule.
** Below average resistance rate to Bionics.

Especially noteworthy for the Iron Warriors considering they reside in the Eye Of Terror, there has been little mutation in their gene-seed as well. Those that do suffer mutation simply replace their mutated limbs with cybernetics. However, there may be some unknown issue which caused them to be afflicted with the [[Obliterators|Obliterator Virus]] (or was it they who made it? It's been confirmed Perturabo and Mortarion worked together on the obliterator virus) More easily - the first ones originated from them.

However, this is rendered null by the fact they are the [[/d/|sick]] [[Honsou|fucks]] behind the [[Daemonculaba]]. Due to its nature, the women themselves may have the gene-seed organs implanted (among other things), or at least the DNA required to be able to quickly grow the organs into a child stuck in their wombs. While the poor, innocent, scared kid inside can become a skinless abomination/mutant, they will normally emerge a genetically stable, gene-seed uncorrupted [[grimdark|skinless adult SPHESS MAHREEN with the mind of that same scared child]]. Suffice to say, this is a sick way of getting to [[Female Space Marines|FEMALE SPHESS MAHREENS]], and is [[Extra Heresy|DOUBLE HERESY]].

==== Luna Wolves/Sons of Horus (XVI Legion) ====
{{Main|Black Legion}}
* Implicitly defective Ossmodula, causing increased cosmetic similarity to their Primarch.
* Implicitly defective Biscopea, causing increased cosmetic similarity to their Primarch.

No real defects, but the tendency for members to look more like their [[Horus|Primarch]] is more pronounced (and possibly more frequent) than it is for members of other legions to resemble their own respective Primarchs. [[Horus Aximand|"Little Horus" Aximand]] was the most notable example of this, but by no means the only one. This gives extra meaning to the "Sons of Horus" thing. In fact, before the Luna Wolves were renamed the Sons of Horus, Luna Wolves that resembled Horus in appearance were known as "Sons of Horus". Ten thousand years in the Eye of Terror has left the Legion's gene-seed more unstable. However, we do know that new Black Legionaries are inducted constantly (seeing as they are the primary generic Chaos Space Marines faction), so its a good bet a large part of theirs is still usable [[grimdark|and that generations of children for millennia to come will be torn away from their parents and families, unfortunate enough to live in the Eye Of Terror, to be inducted into the Legion.]] Furthermore, given that they frequently "recruit" from other chapters and legions with the only real requirement being loyalty to [[Abbadon]], it's not always easy to tell which Black Legionnaires are descended from Horus and which are from other Primarchs, outside of the aforementioned lookalike business.

==== Word Bearers (XVII Legion) ====
{{Main|Word Bearers}}
* Implicitly defective Catalepsian Node.

The Word Bearers suffer a unique "quirk" in their gene-seed, resulting in a psychologically obsessive loyalty to something, be it a man, a religion, or even an ideal. The Word Bearers in turn thus have a much stronger sense of loyalty to their battle-brothers and Primarch than other Chaos Space Marines, helping them to maintain cohesion and avoid treachery, but this loyalty also borders on fanaticism. Otherwise, while given to some instabilities, they have been able to maintain strength.

It has been suggested that Word Bearers have an extraordinary amount of control, both mentally and physically, far more so than normal Astartes. It's been show in their ability to directly control the processes of their internal organs and is attributed as the reason why Word Bearer Diabolists are fairing so well against the Neverborn.

==== Salamanders (XVIII Legion) ====
{{Main|Salamanders}}
* Unique Melanchromic Organ, causing their skin to turn pitch black (so much so that it looks genuinely unnatural) instead of waiting for radiation to happen to fix it.
* Unique Occulobe, causing limited ability to see infrared emissions, referred to as "fire-sight". While not as potent as what an Auspex scanner would be capable of, it can be combined with specialized materials within armor and standards to produce decorations and tactical markings that only the Salamanders can see. This also gives them glowing red eyes, Which makes sense.
* Possibly altered Mucranoid - high degree of heat resistance.
* Possibly altered Biscopea or Lyman's Ear - tend to be somewhat slower moving than other marines, although sometimes it's blamed on the somewhat high gravity on Nocturne or the unusually methodical mindset of it's inhabitants, since they can still run at the same level as any other chapter. (Way back when, they had -1 Initiative.)

While slightly dysfunctional, their gene-seed is pretty stable. Would probably be, like the [[Iron Hands]], a common source of new chapters if not for, again, their extreme decimation during the [[Drop Site Massacre]]. They've since recovered, perhaps a little quicker than the Iron Hands (possibly due to being a little closer to the center and being able to evacuate more marines, As well as still having their Primarch at the time), and while they claimed no official kinship with any successors before the Ultima Founding, there are at least a couple of examples with similar unit markings and tactical dogma.