>>63809822Some orders take vows of chastity, most don't but this is 40k and grimderp so none of them care that much.
In their army book it is explicitly said that novitiates undergo anti-Slaanesh training aka they get bred once by top ranked Schola Progenium/noblemen as their 'tithe' to the Imperium. If they bore a son that kid is going to be a commissar/officer someday and if its a girl they become future SoBs.
There is also a non-militant order that manages and fucks teenage/young adult noblemen to ensure loyalty to the Imperium. Any pregnant battle sister gets pulled back and serves a support role before getting stimmed up after childbirth to go fight again.
There's a book where a battle sister got pregnant by a veteran guardsman and her kid later became a Stormtrooper and she became a Canoness, meeting again on the same battlefield. I think the random Imperial Fist pointed out their similarities and it was revealed that they were mother and son in the end.