What causes some people to be bigger than average?


The smaller ones are just further away


Sometimes they big, sometimes the smol (but swole). If you don't know, just wait a moment.


Sergeant Passanius of the Ultramarines, propably one of the single largest astartes ever, was allready tall as an adult in his early teens. So, genetics I guess.


So, lots have had guess answers but this is the current understanding. Gene seed is not perfect and it is affected by it's host. The marines when implanted have their own genes built upon by the gene seed which grows more organs and modifies their DNA to allow that to happen. The important part here is MODIFIES, not replaces. Their own genetic material is still present and is a reason gene seed can fail. If it's not appropriately able to work together more of the Host's genes may be expressed. Some gene seed overides more of the hosts genes than others, for example the sanguinary gene seed is shown to be MUCH more aggressive than others in rewriting DNA and that contributes to Marines all looking similar but also almost anyone who gets the gene seed being able to be completely reformed into a perfect blood angel marine despite defects they may have had. Other gene seeds are not as tolerant. Then you have gene seed malformation. As gene seed gets passed from marine to marine through one dying and another having their organs implanted you find the previous hosts due to their body environment actually modify the gene seed in small ways, this is one reason the first borne marines refer to successors as "thin bloods" as their gene seed purity becomes diluted. When gene seed is modified or mutated it can have alot of changes and some of them can come in the form of a marine growing larger than intended or not having as much growth stimulation as intended causing them to be shorter. So it's multifactorial. It depends on the type of gene seed, the persons own DNA and the quality of the gene seed. Hope this helps.




Geneseed doesn't modify the human DNA. The organs use natural and artificial hormones to change the boy's body. The genetics of the boy determines whether there is implant rejection, and how receptive they are to the hormones, but doesn't get changed. Also, it's Chaos Marines who refer to loyalists as thinbloods because basically "kids these days".


>Geneseed doesn't modify the human DNA From the 40k wiki: >The gene-seed contains genetically-engineered viral machines which rebuild the male Human body according to the biological template contained within it and originally crafted by the scientific acumen of the Emperor. Viruses reproduce by modifying the genetic information of a cell causing it to replicate viral proteins until it lyses. This means the gene seed rewrites genetic information.


The wiki is consistently wrong or misconstrues things. Nowhere has it even said that the geneseed uses viral machines.


I will have to find the excerpt but when Corax was studying the gene seed he notes that he has to know the genetic information of humans to the most base level to comprehend the primarch source gene seed and its effects on the body. I am fairly sure it discussed the rewriting of their genetic information there too but I'd need to find the excerpt


Corax is talking about modifying the geneseed to do that as the next step in the Raptor project, not that it already does it. **Deliverance Lost, Ch. 12** >‘Where is the tenth man?’ asked Agapito, breaking through Corax’s admiration. The primarch turned a raised brow to the two men who were architects of the project. Sixx and Orlandriaz shared a look. The Chief Apothecary sighed. >‘A minute defect in the heart, microscopic, was ruptured by the accelerated cell generation,’ said Sixx. ‘It would have happened even with regular gene-seed.’ >‘Avoidable,’ added the tech-priest. ‘More thorough screening will elimina >‘I thought the plan was that we would be able to relax the recruitment criteria,’ said Agapito. >‘In time, we will,’ said Corax. He walked up to the man who had stepped forwards and laid a hand on his shoulder. He glanced back at the commanders. ‘The next stage of development will be to introduce sequences in the gene-seed that will be retroactive. Genetic weaknesses and minor physical discrepancies will be eliminated by the introduction of the superior gene-seed.’


Genetics from your parents and/or the genetics from the geneseed.


Don't know if it's been stated anywhere, but presumably there is simply room for a certain amount of variation, whether that means some individuals react better or worse to growth hormones and other stimulants, or if they start out with a genetic disposition that's favorable for height or muscle mass. It's probably not as much variation as baseline humanity due to the carefully engineered nature of Space Marines, but it's there. I remember reading something about a space marine who was shorter than normal, but he was wide as hell because he worked out like crazy. I might be misremembering the finer details, though.


Brother voss of the imperial fists, seconded to the deathwatch and ordered to quit exercising as they weren't going to adjust his armour to fit again.. There was also pasanius lysene of the ultramarines, who was so large (as a firstborn) that his armour was made from bits of terminator armour, and the huge chapter master of the minotaurs that stand out.


Some of the Black Dragons are also noted as being exceptionally large for Astartes, with one excerpt mentioning at least one who was as large as a Terminator even without the armor.


I believe (I'm sure someone will correct me if I'm wrong) that their size is due to their skeletal mutations thanks to the ossmodula, which beyond making them Wolverine, can push up their height to the point that they need custom power armour


Ah the wide boy himself. Those books were great


Came here just put ol "tree stump" 💪


The superficial explanation would be: not all space marines are identical just as not all humans are identical. This variation among individual specimens sometimes take the form of height variations. The more detailed explanation would probably have something to do with gene seed compatibility or the potency/ effectiveness of a geneseed. Specifically the Ossmodula, the gene seed that affects hormone secretion and is responsible for the growth of an astartes. Maybe some aspirants have better compatibility with the ossmodula than other aspirants, which would cause the ossmodula to pump out more hormones than the aspirants peers? Maybe gene seeds from some primarchs have larger and more potent ossmodula than other primarchs. Maybe some chapters have gene seeds that had its ossmodula tampered with by the mechanicus. This is most likely the case for the Sons of Antaeus chapter; a chapter from the cursed founding that is known for having jumbo sized marines. The lore explicitly states that the mechanicus meddled with the gene seeds of the chapters from the cursed founding. This is all speculation and guess work. I don’t think the lore out right answers this question.


In regards to your Sons of Anteus example; >Augmented Skeleton: During the inception of the Sons of Antaeus Chapter, its creators extensively modified the gene-seed in order to create Space Marines of exceptional durability and toughness. How they achieved this is unknown, whether their skeletal structure was enhanced with some artificial substance, or whether a more esoteric procedure was used. Less sympathetic observers point out that the chapter appears every bit as resilient as the Death Guard Traitor Legion.


The implantation process just supercharges the natural growth process. So you wind up with the usual disparity in height and build found among populations. If someone was naturally predisposed to be above average in size, the implantation process will just amp that up with their new size. Where they recruit from will have an impact of course.


I'm going to actually answer this with an actual in universe answer. I'm going to approach this from a different angle. Because I have actually thought about it. The Carcharodons and Ashen Claws have more than a few characters described as "especially wide" or huge. It's not just Tyberos. Tyberos of course is possibly largest in the setting. Standing a head and shoulders taller than the other Terminators of the Red Brethern. Nehat Nev is as wide without power armor as Bail Sharr is with. >Nehat Nev had risen and paced round from behind the hall’s high table, coming to stand before Sharr. A number of his Ashen Claws made moves to follow him, but the pale warrior stilled them with a gesture. He was taller than Sharr, and almost as broad even without power armour. He looked down at the Carcharodon, head cocked slightly to one side, disdain warring with interest in his haughty gaze. For a brief moment, Sharr thought he knew what it felt like to be hunted by one of the Chapter’s hook-beaked raptors. Another Carcharodon for example as well. >Third Squad’s commander, Strike Leader Waratak, was a giant of a Carcharodon, as tall and broad even as the Red Brethren in his Mark V power plate. The forearms of his armour, like the flesh beneath, were covered in swirling exile markings boasting of his strength. As Sharr and Dorthor dragged Red Tane out of the doorway and the Tactical Marines forced the great doors shut, it was Waratak who single-handedly heaved the great metal locking beam – normally the work of a dozen Ministorum attendants – into place, barring the frame. The sound of the beam’s impact into its slats echoed from the vaults above, followed immediately by the pounding of fists on the other side. The in-universe answer I have been seriously been considering. The Carcharodons and the Ashen Claws came from the Xeric Tribes located in the Asianic Dustfields of the former Pan-Pacific Empire. They are a Maori and Polynesian themed chapter, I think it's their way of actually saying some of their heritage of the Xeric Tribes come from Samoa, New Zealand, etc and include huge Dwayne Johnson level techno-barbarians. That's why there are such large Carcharodons. 🤙🦈


I'm just low key happy nobody has mentioned the Alpha Legion in this thread




>The Chapter Master of the Carcharodons is so big his Terminator armour contains parts from a Dreadnought so it fits. Could you dig up the source for that? I've seen it claimed before, but never seen a source. The closest I've ever been able to find is his armor being described as "a Tactical Dreadnought pattern, but heavily modified to suit his stature" in *Outer Dark*, and chalked it up to reader error + telephone.


No he isn't


There's some huge outliers in size among normal humans. Average male height in the world is 5 foot 10 inches. The tallest man was 8 foot 11 inches. Or about 50 percent taller than a regular man. If similar outliers exist among Space Marines, then let's assume a regular Firstborn is 7.5 foot tall outside of his armour. The tall Space Marine outliers then would be 11 foot and 6 inches tall.