User blog comment:Jed Revenant man/Female Space Marines, or, "Can of Worms, opening."/@comment-2253300-20110106070617

Thing about the whole male marine thing is that Geneseed, having been made by men who are genetically based off of a man, does not work with females. I would look at Lexicanum for full details. Anyway, that is why Sisters of Battle are not augmented despite essentially being female counterparts to the Space Marines.