Board Thread:Warhammer 40k General Discussion/@comment-7699236-20150618150629/@comment-25869775-20151213174913

Sterilization and gelding are two very different things people. They could be sterile from the chemicals but we don't know that for sure. Gelding is out of the question though. Like you say they are taken at a pre puberty age, but Astartes have the appearance of developed men. If they were mutilated, then turned into marines, they would be fat, with unmanly voices, no beards or mustaches, less developed facial features like chin and cheekbones, narrower shoulders, etc. But they are not they are developed males. We can conclude that they are intact, so to speak, and have functional hormonal distribution. If anything they are manlier than the average man, frequently described with guttural voices. (See Grimaldus)

Hahaha! Sisters are superior to guardsmen. They are not "thrown into a power armor and then let loose upon heretics". They are augmented; like 6'10 feet tall, pure muscle. Absolutely stronger than the strongesttt natural man. Maybe a Mars priest is stronger, maybe. But they are more forklift than man at that point. Obviously a few tears lower than Astartes but we can assume that they too are drawn from the toughest, mentally and physically, girls they have.

A selective breeding program of pre space marine recruits and sisters is possible but you have to consider that the arms of the imperium that propagate and maintain these programs have little to nothing to do with each other. Also the administration may see this as immoral or dangerous. We already have Astartes treating people like insects, and Sisters burning people without trial. I think hey wouldn't want to maximize this.