There are currently no known female space marines, mainly due to the genetic problems mentioned by others. That being said, the possibility of that changing some point in the future has opened up a bit with the introduction of primaris space marines. The reason I think this is that, if the gene seed can be manipulated to make primaris marines, it could possibly be altered further in the future.

There are currently no known female Space Marines, mainly due to the genetic problems mentioned by others. That being said, the possibility of that changing some point in the future has opened up a bit with the introduction of Primaris Space Marines. The reason I think this is that, if the gene seed can be manipulated to make primaris marines, it could possibly be altered further in the future.