Editing Gene-seed (section)

== Mutation ==

As each new set of gene-seed comes from a Space Marine, requires many years to mature, and many more to be used, there is a lot of room for things to go wrong. This is especially true when desperate circumstances (the impending [[Great Crusade]], or a Chapter being dangerously under-strength) cause Space Marines to skimp on the safety checks and wait periods in order to accelerate Chapter growth. Over the millennia, many flaws have found their way into into the gene-seeds of each Legion, and some of their successors have even more - mutations typically get worse as you make copies of copies. Further mutations have been introduced, of course, in foundings featuring heavy tampering by the Adeptus Mechanicus (see the discussion of the 21st founding, below).
Also one should bear in mind that Legions and Primarchs were artificially engineered to fill different niches, so some of these might be not acquired mutations, but deliberately added quirks to better fit in their roles.
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===No Known Mutations===
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==== Dark Angels (I Legion) ====
{{Main|Dark Angels}}
No defects, unless you consider their <s>rampant paranoia and secrecy</s> STAUNCH LOYALTY AND HONOUR as such. Ties with Ultramarines for "most stable source", so the limited number of Dark Angels successors is usually put down as the [[Inquisition]]'s limited knowledge of the [[Fallen Angels]]. That and the fact that due to successor chapters often working with/take orders from the Dark Angels has lead to the Inquisition to fear the Angels and successors to be <s>"[[Astral Claws|legion building]]"</s> THE MOST LOYAL CHAPTERS DUE TO THE PURITY OF THEIR GENE SEED. Although that would be more credible if they had ever been anything less than a Legion.

==== Iron Hands (X Legion) ====
{{Main|Iron Hands}}
* ''No defects.''
* Noted predilection towards machinery and a disdain towards flesh.

And just to make sure, if there are any, they follow the Bible's advice on offending organs and replace them with holy machinery instead. Would probably be a very desirable source for new chapters if not for the absolute devastation they suffered in the [[Drop Site Massacre]] leaving them barely recovered millennia later and needing all the gene-seed they can get for themselves. Because, you know, even though there has been more than enough time for more than twenty other foundings of whole, brand new chapters, and some of those foundings likely making new foundings of their own, the Iron Hands still haven't had enough time. It also doesn't help how they tend to be total pricks at times. [[Nova Terra Interregnum|Or to have internal disagreements on policy so hard]] [[FAIL|'resolving' them]] [[Sons of Medusa|had Chapter-splitting consequences]]. which does not help building up Marines/gene-seed reserves, and gets you overlooked even more when the Mechanicus is deciding on whose reserves to use for the next Founding.

Alternate take: You need causalities that don't destroy the body entirely to harvest geneseed, or you need to implant it into clones, both of which are unlikely for a chapter that uses augmentations with power supplies that explode like melta bomb and that abhors even the organic parts of their own servitors. No new gene-seed, no new mutations.

==== World Eaters (XII Legion) ====
{{Main|World Eaters}}
I know what you're thinking, but it's caused by an additional cybernetic implant - the ''Butcher's Nails'' - rather than anything in the gene-seed itself. While not ''technically'' part of their gene-seed, it has been carried on as a tradition by all the "successors" that resulted from the Legion's fracturing after the [[Battle of Skalathrax]]. Hell, they were known to be total bros before all the trouble with nails. And now they are little more than [[Kharn|Teamkilling Fucktards]].

Khorne might have given them one blessing though, a sort of extra lives cheat code… But they are limited and are only earned by participating in the arenas.

==== Ultramarines (XIII Legion) ====
{{Main|Ultramarines}}
*''No official defects.'' Considered the most stable and preferred source of gene-seed for new Foundings. Possible predilection towards conformism and communitarianism.
**Due to a lack of any real interesting or identifying traits in and of itself, discussions for reclassifying the Ultramarine gene-seed from the most stable source to the most generic source were in the works. These talks were surreptitiously shut down by [[Who Watches Them|Inquisitor Warden]] for offending his sensibilities.
**Also worth noting is that the Ultramarines, in one of their bro-iest moves, "adopted" a fair number of loyalists from traitor legions after the heresy and are heavily implied to have taken in members of the two missing legions after whatever it was that got them disbanded. There is no real way of telling if an Ultramarines "successor" might be from the relatively stable stock of World Eaters or Iron Warriors. In most cases only a single high-ranking [[Belisarius Cawl|archmagos]] knows the truth, so even the chapter itself (except possibly the command and the eldest brothers) is in the dark about its history.

==== Death Guard (XIV Legion) ====
{{Main|Death Guard}}
*Emphasis here is on ''known'' mutations - there's no actual evidence of Death Guard gene-seed having any problems at all, because we've never gotten any fluff covering any attempts to use the gene-seed from a Death Guard, even though one would assume that by now they'd have the most fucked up Progenoids of any Legion.

During the [[Great Crusade]], the Death Guard had a much stronger constitution than most Legions, leading to their role as the toxic environment specialists. Post-heresy, however, the Death Guard are so diseased that implanting Aspirants seems more or less impossible - however, there have been new Death Guard legionaries who are not defectors from other Legions or renegade Chapters, apparently made with the gene-seed reclaimed by the [[Plague Surgeon]]s. How it functions still, no one knows, though we suspect it has more to do with [[Nurgle]] infectiousness than with the progenoids themselves.

The most overwhelmingly likely explanation is, however, the Death Guard simply jacking loyalist gene-seed from fallen loyalist astartes and loyalist gene-seed stockpiles and using it to create new recruits, as '''every single Traitor Legion with tainted, unusable geneseed does this.''' As per LoS, appears to be a mixture of both, likely depending individually on each Death Guard members level of disease and mutation, supplemented by stolen and possibly altered loyalist gene-seed (see Plague Surgeon).

==== Alpha Legion (XX Legion) ====
{{Main|Alpha Legion}}
<s>No such Legion exists, therefore no such gene-seed exists.</s>
*Were you really expecting ''known'' mutations, or anything else, from this Legion???

In all seriousness; like much of the Alpha Legion, we don't know all that much about their gene-seed. Whatever idiosyncrasies or flaws they have are kept under very tight lock and key. And with their nature of running as individual operatives in and out of the [[Eye of Terror]], to what degree their gene-seed is tainted by the Warp or other means varies from Marine to Marine. Though their knack for secrecy, paranoia, and tendency to subvert the enemy instead of direct combat is probably a notable trait. Outside of occasional Warp-corruption, we ''assume'' it's possibly one of the most stable gene-seeds, probably as much as the Imperial Fists or Night Lords. Something of note; they often use any mutations that they have as a scare tactic, hiding them and then revealing them on the battlefield in order to shock the opponent.
They also use hypnosis and deep-indoctrination more than other chapters, so they may have an altered sus-an and/or catelapsean.
Sometimes it's implied they all look alike (like Alpharius) but sometimes this is said to be due to ''surgical'' alterations, but it could be that the gene-seed does more to alter their appearance than normal, like the Sons of Horus and this is further supplemented by surgery. It's also said that some Alpha Legionnaires tended to be noticeably taller than most Space Marines, large enough to pose as either [[Alpharius]] or [[Omegon]]. This, combined with their unusually short Primarchs and their tendency to look alike, seems to suggest that this was intentional, either by the Legion themselves picking only notably large aspirants or by the Emperor fully leaning into the Legion's whole "smoke and mirrors" theme.

===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.

===Major Mutations===
These Chapters feature at least one problem as least as bad as missing an entire organ, scaling up to the worst issue, where they go World Eaters-level crazy without needing any implants to get there (Blood Angels and Space Wolves).

==== White Scars (V Legion) ====
{{Main|White Scars}}
* Tendency to do whatever they fancy.
* Unrestrained love towards doing [[PROMOTIONS|strange things]] to engines buffing their bikes and battleships to ride into battle while riding into battle.
* A defect called "Chogorian Savagery". Basically it's diet Black Rage, born from when Mortarion almost killed their primarch during the Siege of Terra. This flaw appears in 2 stages:
** Stage 1 - A Moment Unrestrained: The Battle-Brother starts [[RAGE|flipping out mid-battle]] for brief periods, often without realising he's doing so until one of his brothers tells him to take a chill pill.
** Stage 2 - Suppressed Rage: The Battle-Brother becomes extremely prone to outbursts of temper and quick to anger.

===== Mantis Warriors =====
{{Main|Mantis Warriors}}
* Possibly Melanchromic Organ as all have green eyes and black hair of their Primarch.
* Malfunctioning Preomnor gland (possible explaining the cause of the gene-flaw of the other White Scars chapters)

Their mutation called "Battle Haze" causes their Preomnor gland to secrete a potent neuro-toxin that permanently changes the Astartes' physiology; the Space Marine is overcome by a feeling of the need for forgiveness for his many sins and shortcomings and a dramatically increased reverence for the Emperor; and increases his neurological reaction rate to that only achieved in near-precognitive states by most psykers and increases his already superhuman strength to a great extent. However, this physiological change is irreversible and the Astartes' sight becomes tunnelised to the point of no longer being able to notice anything in his field of view that is not a target or a foe. Much like the [[Death Company]] of the Blood Angels, the Mantis Warriors organize Battle-Brothers who have been lost to the Battle Haze into specialized units called "Mantis Religiosa".

===== Destroyers =====
{{Main|Destroyers}}
* "Chogorian Savagery" turned up to 11. To the point even other White Scars question the stability of the Destroyer's geneseed. More evidence that the flaw stems for the gene-seed of the White Scars, and not from what population they are pulled from. Probably at least a bit psychological and genetic memory related, what with the most psychotic Scars forming this Chapter in the Second Founding.

==== Imperial Fists (VII Legion) ====
{{Main|Imperial Fists}}
* Missing Betcher's Gland (no acid spit).
* Missing Sus-an Membrane (no suspended animation).
* Possibly increased pain tolerance and/or a tendency towards masochism.

Despite missing two organs, the Imperial Fists gene-seed is considered to be amongst the most stable and most manly sources. It is the second most desirable source of gene-seed for Foundings. ''Second'' to the Ultramarines, of course. The Fists however, display a constant need to punish themselves for perceived failures, both real and imagined. While this is barely noticable in the primogenitor chapter, several successors manifest more pronounced versions of this flaw.

Missing Sus-an Membrane is also a big deal, as it removes a "safety net" most other chapters have, and most times when Imperial Fist "falls in battle" he actually dies for good instead of passing into coma from which he could be brought back later if marines win the engagement and recover his body. That's why Imperial Fists and all their successor chapters need multiple recruiting worlds. Silver lining though is that sons of Dorn don't run the risk of being captured by Chaos and brainwashed if they fall in battle and their body is then recovered by forces of Chaos instead of allies.

* Complicated by the [[War of the Beast]], in which the Imperial Fists were ''literally wiped out to the last man.'' In the aftermath, their successors got together to donate gene-seed to reconstitute the chapter, making their post-Beast gene-seed a chimeric melting pot of separate mutations and oddities. Additionally, it's not confirmed whether the mechanicus were holding and offered stocks of original, untainted gene-seed as part of this process. Even [[Primaris Marines|Primaris]] marines who were made with the original stuff (and in some cases are original legionaries) may be different as it's not clear what effect Primarisification has on the gene-seed or if it's possible to make firstborn from it. In short; the Imperial Fists gene-seed may be unique among loyalist chapters in that it [[Grimdark|simply no longer actually exists.]]
** Except, hilariously, in some [[Iron Warriors]], who take a particular spiteful delight in [[Blood Ravens|stealing]] their arch-nemeses' progenoids.

===== The Excoriators =====
* A mutation with some similarities to the Blood Angel's Black Rage, known as "Dorn's Darkness.". Those affected enter a dream-like state in which they relive the bottomless woe and paralyzing fear of Dorn's darkest moment: the moment he saw the Emperor near death after the battle aboard the ''Vengeful Spirit''. They can't care for themselves while in this state, and don't recognise anything happening around them. 
** Basically, if the Black Rage is unbridled [[RAGE]] unbound, Dorn's Darkness is crippling, ruinous depression.

===== Crimson Fists =====
* A mutation similar to Dorn's Darkness, known as "Only Honour In Death". The "curse" causes a massively increased willingness to fight to the last, holding their ground with a siege-like mentality which will see them triumph or die in the attempt the more foes that the Astartes faces, and the longer they are in combat, the more likely and stronger the curse becomes, making them feel emotions much like what Dorn felt during the [[Perturabo#Iron_Cage_Trolling|Iron Cage Incident]]. When succumbing to the "curse" the affected Battle-Brother sees only death: the death of their comrades, the death of the world, and the death of their foes. The curse is seen to come in three stages:
** Stage 1 - No Retreat. As the odds mount so does the Battle-Brother's stubborn refusal to retreat, seeing only the glory and honour in defeating such overwhelming foes if even the barest glimmer of victory remains. The Battle-Brother will even continue to fight, even if the Codex Astartes does not support that action, until there is no hope of victory left.
** Stage 2 - Suffer not Defeat. The Battle-Brother decides [[Red Scorpions|he'd rather die fighting than take a step back or listen to reason]], even when there's little reason to do so.
** Stage 3 - Unto Death. [[Blackshield|The Battle-Brother becomes hell-bent on sacrificing himself for victory or the safety of his brothers, regardless of how badly hurt he is.]] He'll happily accept suicide missions or near-enough suicidal tasks. Essentially Black Rage 2: Fists Boogaloo.

==== Space Wolves (VI Legion) ====
{{Main|Space Wolves}}
They actually have two different implanted DNA sources: the second is the Canis Helix, which makes them viking werewolves (long canines, tough skin, awesome sense of smell, animalistic [[RAEG]] in combat) or, if one is really unfortunate, into a giant [[Furry|wolf]] ([[Thunderwolf Cavalry|the ones they ride at that]]), and their super-unstable geneseed, which can't function without pre-implanted Canis Helix and has been found to be incompatible with any populace outside of Fenris. For the most part, they get around this by just founding tons and tons more Space Wolves than the [[Codex Astartes]] would normally permit, meaning that they ''still'' tend to have tons of chapters' worth of marines on call. Of particular note are the [[Wulfen]], who are Space Wolves who happened to be in the Warp for over ten thousand years. Instead of being mutated into [[Chaos Spawn|unmentionable gribbly beasts]], they managed to turn into literal werewolves with savage strength, meaning there's a possibility the gene-seed has a factor that lets them resist the influence of Chaos.

While many factions within the chapter are proud of how "potent" their gene-seed is, plenty of Space Wolves have constantly labored to stabilize their genome in order to found successors to cordon off the [[Eye of Terror]], and crusade against the [[Thousand Sons]], a plan called "the Sons of Russ." Once, [[Wolf Brothers|they got really close]], which [[Magnus the Red]] didn't like, so he took his Marines and bumped off the Wolf Priest in charge (and generally wrecked things for the Space Wolves), using some [[Tzeentch|Tzeentchian]] trickery to get an opening. In short, he [[gets shit done|got shit done!]].

===== Wolf Brothers =====
{{Main|Wolf Brothers}}
See Space Wolves above turned up to 11. As in the entire chapter devolved into werewolves.

==== Night Lords (VIII Legion) ====
{{Main|Night Lords}}
* Defective Occulobe (causing them to have black irises & sclera, enhanced night vision but more sensitive to bright light.)
* Malfunctioning Melanchromic Organ (their skin is always pale and their eyes are always dark. Much like the Raven Guards.)
* Occasional visions of the [[grimdark]] future, even if not a psyker.
The Night Lords are officially the most stable of the Traitor Legions, a trait often put down to the fact that they rarely dwell in the [[Eye of Terror]]. That, and they don't even like Chaos or the gods. What little mutations there are are usually upon their Sorcerers...what ones have survived do not have them anymore either. There is one defect on Curze's Geneseed, and that is the Occulobe defect, causing them to have black irises & sclera, and astonishing sight in the dark, even more than a normal space marine. Although, there is a bad side of this effect: Light hurts their eyes like hell, and blinds them for a short time. Also, Curze's gene-seed may have passed onto psykers within his Legion his "gift" of seeing the future in the worst way possible, and as scenarios that become self-fulfilling prophecies. In one case, it was found out that the Primarch's "gift" was actually the side effect of a marine's body slowly rejecting the gene-seed. Prior to receiving this gift, he never demonstrated '''any''' psychic capability. Even so, this situation is rare.

==== Blood Angels (IX Legion) ====
{{Main|Blood Angels}}
* Malfunctioning Omophagea implant (Occasional bouts of temporary [[Rip and tear|bloodthirsty, genocidal rage]], otherwise known as the [[Red Thirst]].)
** Occasional bouts of ''permanent'', [[Rip and tear|bloodthirsty, hallucinatory, genocidal rage]], better known as the [[Black Rage]].
* Extreme longevity.
* Can turn even mutants to Astartes, extremely adaptable.
Stable, but flawed. Prior to the [[Horus Heresy]], [[Sanguinius]] discovered that some of his sons were beginning to suffer the [[Red Thirst]], where they would descend into a thirst for blood, whether [[human]] or [[xenos]], in a blind rage. If that wasn't bad enough, as a result of Sanguinius's death at the hands of [[Horus]] imprinting itself on their genetic memory (or something), all Blood Angels and their successors have the [[Black Rage]]; a berserk rage where they [[Derp|believe themselves to be Sanguinius during his final battle]]. Meaning that Fucking Horus quite literally hit Sanguinius so hard that his grandchildren's-grandchildren's-ad-infinitum-children still feel it. Notable due to the age of the flaw it means that it does not register on genetic purity test since, as a first founding legion, any additional geneseed would be compared to an already 'tainted' baseline.

===== Angels Encarmine =====
* See the Blood Angels above, but with the Black Rage turned up to 10

===== Flesh Tearers =====
* See the Blood Angels above, but with the Black Rage turned up to 11.
* Also Red Thirst turned up to 10.

===== Knights of Blood =====
* See the Blood Angels above, but with the Black Rage and Red Thirst turned up to 12 (and the dial snapped off).
** It got so bad that they were declared renegade and not refounded after they sacrificed themselves to save the Flesh Tearers at Baal.

===== Blood Drinkers =====
* Malfunctioning Mucranoid (skin glands atrophy, causing the pores to close. Named the "Weaver" by the Blood Drinkers)
* See the Blood Angels above, but with the Red Thirst turned up to 10. Due to further mutation of the Omophagae implant.
* Black Rage turned down a notch, but this isn't genetic. The entire Chaplaincy is in on a Daemonic pact to reduce its impact.

===== Lamenters =====
* All the problems of Blood Angels (tho it took them longer to show).
* Being overly emotional sad sacks, but this is as justified as it gets because...
* Unlucky as all fucking hell. Best way to describe it is fate itself is just constantly giving them the middle finger. This might have something to do with them coming out of the Cursed 21st Founding.

==== Thousand Sons (XV Legion) ====
{{Main|Thousand Sons}}
* Increased chance of bringing out psychic powers, as well as amplified psychic power.
* Recipients subject to a high rate of mutation, called The Flesh Change; unstable.
The most unstable genome in the Space Marine legions, the Thousand Sons suffer from the Flesh-Change, a problem that caused Thousand Sons to mutate spontaneously. [[Magnus the Red]] fixed it, with some "[[Just as Planned|help]]" from [[Tzeentch]]. After the [[Horus Heresy]], the flesh-change came back with a vengeance. [[Ahzek Ahriman]] tried to fix it with his Rubric, and he did end up stopping the flesh-change... by turning all non-[[psyker]] Thousand Sons into dust; sorcerers also had their powers enhanced in addition to no longer suffering ill-effects from the Flesh-Change. So while theoretically, the Sorcerers of the long suffering Legion can provide gene-seed, in practice, it's corrupted so often that few will ever make new Marines. Thousand Sons specifically hunt for healthy and stable psyker boys to implant them with their oh-so-rare gene-seed to ensure the recipient would become a sorcerer. If "Masters, bidding!" TS character words to be trusted, Thousands Sons found a way to implant their progenoids into grown up men (so they can teach and test them for longer before implantation), and perform a scaled down Rubric on them to prevent the Flesh Change. According to Phil Kelly they also replenish their numbers by summoning back souls of destroyed Rubrics, and Magnus supposedly can bring back Sorcerers he isn't pissed off at, so gene-seed wouldn't matter much to them. It is known that Magnus the Red used his knowledge of Biomancy to turn his mentor Amon into an Astartes despite his old age, so its possible this technique was passed down to his Legion.

==== Raven Guard (XIX Legion) ====
{{Main|Raven Guard}}
* Malfunctioning Melanchromic Organ (their skin is always pale and their eyes are always dark. Anti-Salamanders, basically.)
* Missing Mucranoid (no super-sweat).
* Missing Betcher's Gland (no acid spit).
* Occasional bouts of suicidal rage (Luckily for them this is not permanent unlike a certain other chapter.)
While their primary gene-seed is decently stable, when under extreme stress a percentage Raven Guard warriors will lapse into bouts of suicidal rage known as Ash Blindness or Sable Brand. This is rarely permanent, but occurred with enough frequency that [[Corax]] would organize these warriors into the [[Moritat]]. Their missing and malfunctioning geneseed organs is a result of [[Corax]], out of desperation following the [[Drop Site Massacre]], delving into use of forbidden lore and archeo-tech from days long past to accelerate gene-seed maturation, and try to boost his Legion's numbers after their losses during the [[Horus Heresy]]. He was successful, until the [[Alpha Legion]] decided to make the whole project go FUBAR. The subsequent 'Marines', if they can be called that, were numerous, but were barely controllable monsters and/or would simply die off as a result of the extreme imbalances in their dispositions. Presumably, a few of them would even have functioning Progenoids, let alone usable gene-seed. Due to the law of averages though, at least a FEW would have had to been stable enough, and is being worked on secretly by the Raven Guard Apothecaries and associated [[Adeptus Mechanicus|Mechanicus]] Biologicans.

Otherwise, despite being pretty fucked up by the [[Drop Site Massacre]], they've mostly recovered (thanks in no small part to having the ''only'' loyalist Primarch to get away from the Massacre in one piece) and do still contribute to successors [[Death Spectres|here]] and [[Raptors (Chapter)|there]].

===== Raptors =====
* Same as the Raven Guard, except they have functional Bletchers Glands (making them more like [[Night Lords|another black-eyed / pale skinned gene-line]]).

===== Death Spectres =====
* Similar Melanchromic Organ as Raven Guard, though a specific shade of albino and their eyes universally glowing red (basically albino Salamanders).
** also gives them a 100% certain chance of alopecia. (They are genetically bald From the day they were born till the day they die)

==== Marines Errant (Ultramarines Successors) ====
* Suffer a psychological flaw called "Crusaders Call", which makes them unable to refuse the call for a crusade. This flaw manifests in three stages:
** Stage 1 - Unending Valour: The Battle-Brother has become filled with pride in the history of his Chapter's bravery and devotion and sees his own existence as a vital part of continuing its traditions. When his squad is required to do its duty he will make sure that it is carried out, squashing any doubt his fellow Battle-Brothers might have or any weakness they might show in the face of honour.
** Stage 2 - Duty through Sacrifice: True duty can only be proven in death or an equally potent sacrifice, a fact which is known to all true servants of the God-Emperor. The Battle-Brother knows that to prove himself he must be the one to stand in the way of the blade or shield his comrades from the blast, so that there can be no doubt about his devotion or his loyalty to the Emperor.
** Stage 3 - Lead the Charge: In boarding actions, the greatest honour goes to those first through the breech and first to face the foe. The Battle-Brother accepts that he must take this role as his honour demands it, and it is just another way to prove his courage and loyalty in the eyes of his peers. If there is a choice or a chance to lead a charge or be the first to face the enemy, the Battle-Brother must take it. Furthermore he will seek out such opportunities, volunteering for dangerous duties if they mean he will get to lead others into the fray. In combat, the Battle-Brother will also seek out the most dangerous or powerful-looking foes, even at the cost of ignoring closer or more pressing enemies to his brethren's tactical disadvantage.

It is unclear if these are actually geneseed flaws or cultural issues ascribed to geneseed.

==== Soul Drinkers ====
* Enhanced Omophagea organ (In addition to gaining the consumed creature's memories, the Soul Drinkers could also experience the creature's emotions during the events recorded in their memories as a result of their mutation). This is despite being a 2nd Founding chapter, such that their gene-seed shouldn't have had flaws like that. And the gene-seed was enhanced, not degraded....

==== Blood Ravens ====
{{Main|Blood Ravens}}
* A mutated Catalepsean Node - gives them perfect memory recall, but unable to enter REM (deep) sleep.
* Increased chance of bringing out and enhancing psychic powers.
* Small tendency towards mutations (hurr sounds like [[Thousand Sons|any other Legions]] we know of?).
* Horrendously massive tendency to develop kleptomania.
* The pores in their scalps secrete a substance not all too dissimilar to hair gel, often resulting in a higher tendency to develop hair-etical hair compared to other chapters.
** Alternatively, the pores on their scalps may prevent hair from growing altogether, giving the marine Astartes-pattern baldness. [https://www.youtube.com/watch?v=UZfvIg_M5yE It has been long thought to be a terrible weapon to behold.]
* Unknown mutation referred to as "unavailable voice actor syndrome" that results in their voices changing every few years.

==== Carcharadons ====
* Malfunctioning Melanchromic Organ (pale skin and black eyes like the Night Lords and Raven Guard)
* Mental deterioration called "Chill of the Void". This deterioration proceeds like a mini-version of what Konrad Curze went through as he became the Night Haunter. This deterioration occurs in three stages:
** Stage 1 - Coldly Formal: The Battle-Brother withdraws even more from the company of his colleagues, taking refuge in a chill and formal demeanour. In addition, the Battle-Brother tends to speak almost entirely in High Gothic when addressing a non-Carcharodon, although they can speak in Low Gothic if need be (but they really do not want to).
** Stage 2 - Merciless: The Battle-Brother does not tolerate any enemy, whether xenos, Heretic, or even fellow humans who may have been misled into rebellion against the Imperium's rightful rule. The Battle-Brother grimly executes any opponent he encounters, even if they have surrendered, possess valuable intelligence, or are not front-line combatants.
** Stage 3 - Silent as the Depths: The Battle-Brother withdraws almost entirely from interacting with others. He will not lead squads and will almost always carry out missions on his own.

==== Black Dragons ====
* Extreme Ossmodula defect. causes them to grow bone spikes all over. Including full on Wolverine type claws from their arms.
* Moderate Betcher’s Gland defect. Their mouths, both inside and lips, are usually black in colouration. So too, their tongues, which taper to a sharp point like a dagger.
Also causes purple venom to be secreted from their teeth (which resemble fangs) and their tongue.

==== Flame Falcons ====
* Spontaneous combustion into warp fire.
* Increased abilities from said spontaneous combustion instead of horribly burning to death.

==== Minotaurs (21st Cursed Founding-type) ====
* '''ABSOLUTELY BATSHIT GOD DAMN ASSFUCK INSANE'''

These guys had....problems....big problems. They'd basically wipe their asses with any battle plans made by other Imperial forces, before bee lining it to the nearest horde of enemies (not bothering with any of that pussy shit like "recon", "intel", or "even bothering to look out the window at the enemy") and rushing into melee ranges to [[RIP AND TEAR]]. But, this doesn't apply to the original and current units. You see, the Minotaurs chapter have a good chance of actually being a cover to get a loyalist (they had missed out on the Heresy entirely due to their distant posting and spent the interim years unaware of the situation holding the frontier) Iron Warrior garrison unit rediscovered in the [[Great Scouring]] legitimized by the [[High Lords of Terra]]. See their article ([[Minotaurs]]) or the [[Traitor Legion Loyalists]] article for further details.

==== Sons of Antaeus ====
* Unknown mutation that makes them exceptionally durable and tough. To the point of easily being a match for the Death Guard (who are boosted by Chaos energies).

==== Storm Giants ====
* Unusually physically strong, even by Astartes standards. Speculated to be from a mutation or alteration in their Biscopea.

=== A Note On That Sick Fuck Fabius Bile ===

[[Fabius Bile]] is fucking insane. I mean shit, his labcoat is made of <strike>human</strike> ASTARTES skin - normally only [[Space Wolves]] and [[Night Lords]] wear clothing made of that stuff. While originally the Chief Apothecary of the Emperor's Children, he is now a freelancer. His goal even before the Heresy was to find and unlock the secret to the creation of the Space Marines. In the [[Warp]], he provides a valuable service to the Chaos Legion warbands and their auxiliaries of billions more regular Chaos humans - while often millions strong even now, the warbands still need to replenish their numbers. Considering how many die and how often they are away from any place where they can produce more, that's a lot. Even with slave raiding into the Imperium, child abduction both in and out, breeding centers (stop touching yourself), and many [[Daemonculaba|other creative ideas]], it's still not enough. Fabius provides services of human cloning, along with gene-seed production, among his many skills. As he is not a super-devotee of Chaos, the gene-seed he has and makes is some of the least corrupted found within the [[Eye Of Terror]]. Of course, he fucks this all up by hopping up his own warband's clones with the same psycho drugs and shit that make monsters out of men. Lore hints that his genetic tinkering is far more than we have been lead to believe - much of his 'changes' to even the standard human genome are genetic and now passable by both men and [[Female Space Marines|women]]. Even now, the Imperium is trying to hunt and eradicate what they call his '[[Twilight|New Men]]'. He also has access to a small quantity of what is alleged to be the blood of the Primarch Sanguinius. Why did he get that last part? To clone the Emperor. Never let it be said that this fuck, sick as he may be, lacks ambition.
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===21st Founding ===
{{Main|21st Founding}}
Over the millennia, further mutations have afflicted the many Successor Chapters, but the 21st or "Cursed" Founding deserves a special mention, because a bunch of [[Adeptus Mechanicus|tech-priests]] decided that they wanted to try and fix the flaws, but failed so hard they actually created some new ones.

* Bursting into Flames: Yes, the [[Flame Falcons]] really were covered in fire. The Flame Falcons thought it was a blessing from the [[God-Emperor of Mankind]], but the [[Inquisition]] disagreed, and sent the [[Grey Knights]] to wipe them out.
* Bone Growths: Due to a malfunctioning Ossmudula, the [[Black Dragons]] suffer a bone solid growth to harden and extend from their forehead and forearms during times of stress. The ones on the forearm can be used as weapons against unarmored opponents, so they decided to coat them in adamantium. So in essence, they're space-Wolverine-after-the-bone-claws kind of guys. Issue is that this is a very visible mutation, and as this is the [[Grimdark|grim]][[Derp|derp]] Imperium, mutations from the sacred human form are EVUL, even if they are fucking awesome.
* Indestructibility: The [[Sons of Antaeus]] are much tougher than normal marines, and nobody knows why. Some speculate something about a super-reinforced skeleton, some say it's [[Nurgle]]'s doing, etc. The only real truth to it is that there's some sort of mutation present in the gene-seed.
* Bad Luck: The [[Lamenters]] chapter's modifications seemed to have fixed the Red Thirst and Black Rage, but as a trade off they seem to be cursed with some of the worst possible luck, essentially giving up the Khornate Curse for a Tzeentchian one. Many other chapters of the 21st Founding were also cursed with bad luck but the Lamenters are the only known ones that didn't get wiped out by it so that may say something about how badass they are.

=== A Note On Implant Organs/DNA Elsewhere ===

While the SPHESS MAHREENS are the most widespread users of artificial glands, organs, and such, they are not the only ones. [[Inquisitor]]s likely have access to organs or other artificial mutations they require thanks to their influence in the Imperium. Depending on what world they hail from and its beliefs, Imperial Guard regiments and PDF may also have artificial organs, or even whole new ones derived from millennia of mutations, which of course has certain advantages. Furthermore, Warp Exposure can result in a change of the functions of organs - a simple example of this is the [[Cadia]]ns, who nearly universally have powerful, violet colored eyes. [[Gland War Veteran|Gland Warriors]] were an [[Adeptus Mechanicus]] project to help legions of Guardsmen heading into battle against a [[Tyranid]] hive fleet. They were to do battle in an incredibly toxic and hard environment, and a variety of experimental organs and DNA strands were utilized - including organs that would secrete stims, painkillers, and various medical drugs, more powerful natural air filters, and the like. While only [[grimdark|three survived]] the whole campaign in the end, the AdMech was pleased and took the three to be debriefed.

It is also noted that Gene-seed can be decoded, but it requires eons of knowledge about biology, medicine, and so on. Only the Emperor or AdMech, with their advanced equipment, is able to do so (and even the AdMech couldn't fully work it out). The hard part is to decode the "impossibly complex" amino acid chains of the gene-seed (which FYI makes no sense, since DNA is encoded in nucleic acid base pairs, and amino acids are used to construct proteins but whatever) and extract the necessary information encoded within the Gland's stored zygotes. [[Thunder_Warriors|Arik Taranis]] was able to decode it in a dusty, old, half-broken lab—with a box of scraps—using the knowledge gleaned by just watching the Emperor work, and remade it to fit in his Thunder Warrior body.

[[Category:Warhammer 40,000]]
[[Category:Space Marines]]