Salamanders have normal human families and friends, and one of the Space Wolf commanders falls in love with a girl(without really realising what happens in his mind, WHAT IS LOVE?).
GW hasn't even implied that space marines are castrated, rendered impotent or have giant space marine cocks that can rip women in two.
It has been mentioned in the fluff, that Space Marines are either taught, or conditioned not to care for women.
However, a large part of chapters with close ties to civilians or chapters composed out of barbaric or feral space marines don't care for such rules.
Combine this with the fact that in Rogue Trader, space marines had whole harems of sluts that were in the battlebarge rubbing their armour and polishing their bolters, you can bet that most "Don't give a fuck" chapters are perfectly fine to stick their penis inside a woman...
Since GW never mentioned space marine children, it is safe to say that space marines are sterile, perhaps a failsafe to prevent the birth of "incomplete space marines", killing child and mother.
Of course, Fabulous Bile has no moral qualms to mess around with such things... :)