Editing Gene-seed (section)

===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.