Ok I have been looking over countless forums other then this one regarding the possibility of female space marines and I must say the possibility is 80% but being allowed is about 20%.
The reason for this lets take a step back in the past in human past time where males are dominate and women was not no this is not a sexist attack this is just how history Is and was. There are other reason a female was not allowed to go to war due to distraction of seeing the opposite sex being killed outright could be more horrifying then someone of the same sex and the horrors of a woman being captured that. Or most men back then justified there manliness by saying woman are weak and such this could be the very reason women are not allowed to be space marines hence look at IG no real speaking of female IG as they are all male even in the fluff there is very little on female IG command and such.
This can also apply to why space marines are extremely xenophobic in history those of a different race to some cultures was deemed lesser then there cultures and the only way to deal with them was slavery or put to death.
Now the biological sense with tech this high in the 40k having the ability to use geneseeds on a human regardless of sex should not be a problem after all were in the year 2014 and we have sex change's I think in 37986 years they will be able to implement geneseeds regardless of gender.
What is everyone else take on this please try to keep things civil.