Can there be Female Space Marines?
According to official fluff from the first Index Astartes book, Marines MUST be men. They are the Sons of the Emperor, based upon the Emperors and the Primarch’s genes. Both the Emperor and all known Primarchs where male, and thus implants made from their genetic structure can be argued to be x/y chromosome based and male compatible. The reason to Marines being male has to do with that the Space Marine implants are not compatible with females. Supposedly due to the Black Carpace (probably a nerve system allocation problem), which allows a Marine to interact with his Power Armour through nerve impulses; is not compatible with females. – Supposedly this is also tied in with the body’s testosterone production ability and how the nerve-ends fuse with the synth-nerves in the Black Carpace.
