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Why are there no female Space Marines?

Have come across some theories which range from the models not being up to scratch, to lore that Space Marines are almost not human, but none of these give a definitive answer.

There are female Imperial guardsmen and there are Sisters of Battle (one of the reasons the sculptures not being up to scratch is a terrible argument).

Anyone have any ideas?

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The space wolfs books which detail the rise of Ragnar shwo the recruitment process – Marriott81 Mar 20 '14 at 12:38
Possible: the gene seed used to alter them is derived from the all-male primarchs and is thus incompatible with female genes? – AncientSwordRage Mar 20 '14 at 14:11
Maybe there are women recruited, but after being altered to become a Space Marine they look just like men. Similar to the Borg. – Xantec Mar 20 '14 at 16:00
@Marriott81: to clarify: Royal Marines = the UK marine corps, and Games Workshop, the company that makes WH40K is a UK company. – Michael Borgwardt Mar 21 '14 at 11:34
@Xantec, the Borg, or Dwarves. B) – eidylon Jun 16 '14 at 19:47

The in-universe answers I have seen are twofold:

Firstly the Primarchs were all male; space marines are created using their gene seed and it reacts poorly to being implanted into a female.

As others have pointed out, from Lexicanum we have:

They must be male because the zygotes are keyed to male hormones and tissue types.

Secondly (and possibly most importantly) the Imperium of Man is a place where tradition and ritual are treated as important above all other things. Space marines were male when the Emperor created them, so they will ALWAYS be male. To even think otherwise is heresy.

From an out-of-universe perspective; Games Workshop first created the Space Marines in the 80s to appeal to 13 year old boys. Back then the idea of girl space army men was probably not in vogue.

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it reacts poorly to being implanted into a female : This sounds like you've seen examples. Is there a source for the positive assertion? +1 for the tradition though. – Xantec Mar 20 '14 at 16:19
@Xantec Somewhere, I think maybe an old issue of White Dwarf. – evilscary Mar 20 '14 at 16:19
I may have just found this: " They must be male because the zygotes are keyed to male hormones and tissue types." whilst looking into it, from here:… – Marriott81 Mar 21 '14 at 16:18
@marriot81 could you edit that into your answer? – AncientSwordRage Apr 23 at 19:35

The Adeptus Astartes are the Space Marines, and are (so far as I know) all male.

But don't despair for the women, they are not left out of the never-ending war. The Adepta Sororitas or Sisters of Battle is the women's division of the forces of the Emperor. The Sisters tend to operate more as an arm of the Inquisition than in "traditional" theatres of operation. Check the wikia link for more in-depth information on this chapter.

I also like the comment @Pureferret has that the geneseeds for the Adeptus Astartes are taken from the Primarchs and thus are inherently male DNA, and thus may be incompatible. I'm no biologist, but this does sound like it makes some sense too.

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I know that the reason is that the SOB order is not allowed Men at Arms which is why they are all female, but I was curious about the Smurfs and the like – Marriott81 Mar 21 '14 at 16:13

The Imperium has actually lost the technology required to create new gene-seed, especially on the level of a Primarch. Many people have tried, but have failed. The closest that anyone got to creating new gene-seed was actually the Space Wolves, but Magnus attacked Fenris and destroyed the research lab there - forever keeping the Space Wolves from creating any successor chapters. They made one before, but that chapter was corrupted by Magnus himself.

The Emperor did know of Alpharius Omegon, remember that he created both of them. It may have not been planned for the embryo to split, but that's what it did and it had to have happened before Chaos threw the Primarch's across the galaxy. So, the Emperor was aware of the twins but kept it secret for unknown reasons. I believe in one of the books in the Horus Trilogy it briefly discusses when the Emperor found the Primarchs and knew them both to be twins.

Woman would not be ideal candidates to be Space Marines for several reasons.

  1. Most male neophytes die during the organ plantation. You need physically fit candidates, and one's that have strong bodies at a younger age. Young girls would die right out from the procedures.
  2. The Primarch's gene-seed would not be compatible with the genes of a girl, and the two different genes would destroy each other. Killing the host.
  3. Space Marines are an icon in the Imperium, a woman could never be seen as such. The Emperor created the Space Marines from men, thus they will stay as men - even though it's impossible for women to actually become a Space Marine.

The closest you'll get to female Space Marines are the Sisters of Battle.

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Another way to think about it is that the gene-science used to create the Primarchs and marines was exceptionally difficult. Neither the Emperor nor a similar powerbroker ever succeeds in replicating the same Primarch -> Geneseed relationship again.

Given how precarious the geneseed mutations of male candidates were found to be, it stands to reason that there simply was not enough expertise to then also create a similar process for female marines. Even before the Heresy it's well known among the Primarchs, Malcador and the Emperor that several legions possess unstable geneseeds. It's even hinted that at least one of the two lost legions suffered the fate of expungement due to faulty geneseed. Hence, a process as finicky, and frankly error-prone, as the creation of a space marine probably never gets to the point where the powers that be consider expanding to female subjects.

Also note that the Emperor's Custodians are also all male. It could simply be that the gene enhancement techniques developed during Terran unification focused only on male physiology too. There was not a need for more warriors so much as an efficient and trusted cadre of super-human ones, the Adeptus Custodes. If so, again the need for investing research and development into female enrollment is not needed when a small number of elite male warriors would suffice.

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Because of how they were engineered only men can accept the gene-seed of the male Primarchs. If there were female Primarchs this would have been possible, but because they do not exist this is not possible.

Do note that in one of the recent Horus Heresy novels Malcador the Sigilite mentioned to Rogal Dorn that he once advised the Emperor to make some of the Primarchs female because they would lack the rivalries and proneness to infighting common amongst brothers, and that some sisters thrown into the mix would lessen this risk. Rogal Dorn was not amused by this, and even His Imperial Majesty was royally flabbergaste that Malcador suggested this with a straight face.

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What is known of Space Marines gene-seed transformation are the following:

  • the Emperor, whether lying or truthful, states that only men can be Space Marines; so, while this does include transwomen, it does not include women or intersex people;
  • whatever the circumstance, scientific progress by the scientific method and empiricism would be deemed heretical due the Imperium/Mechanicus's obsession with STC technology; so, if one wants to mess around with the Emperor's line of experiments, it would have to be done very discreetly, which would still probably be noticed by Inquisition, so the only way around that is to be part of the Inquisition. Or you could try to take deep into Mars in the old parts of the Tech-Priest civilization, which also comes with its own problems.

As Space Marines, Thunder Warriors, and Custodes are not all the same thing, and the Emperor specifically was talking about Space Marines, then it can be assumed that Thunder Warriors and Custodes (the most powerful of the three), can include women and intersex people.

It should be noted this is quite literally the only thing women can't do in the Imperium. They can join any other branch of the military and attain any government or order position or anything in the professional world besides being a Space Marine and all humans of the Imperium are citizens holding equal rights.

This is assuming of course that aspect of Imperial law, of equality, is actually enforced throughout all the planets of the Imperium, but I suspect that where the Adeptus Sororitas,the Adeptus Mechanicus and the better groups of the Imperial Guard, Knights, Ordo Tempestus, Imperial Navy, Adeptus Astartes and the Arbites are, it'll be enforced. I put the Tech-Priests up there because they would find sex and gender equality illogical, so they have that to be thanked for despite their other shortcomings in human right.

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well it would seem to the average lore follower that all the Primarchs were male, however, upon closer inspection of the history of the ultra marines, there is a segment that many of the lore followers overlooked. the two lost Primarch's, whose statues were eventually removed from the palace on terra were never really discussed in the series by the loyalists, but instead were mentioned by the horus traitors. it's important to note that gender was not mentioned for these two primarchs, secondly the primarch of the alpha legion had a twin that emperor didn't even know about! so there was a slim chance of the two being females?= female space marine gene seed? however, because horus mentioned them at all, it's a safe bet that they were already killed off by the forces of chaos, but what's stopping the imperium of man from creating a new set of female primarchs, or even just one, so that even the lowly female guardsman could become a space marine. and wage all out war against the enemies of the empire?

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Welcome to scifi.stackexchange. It looks like your answer could have something useful in it, but in its current format it is hard to understand. You might want to edit it to make your point more clear. – numaroth Oct 1 '14 at 20:25

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