Now, on to the "how is this possible?" question. First of all, of course it's not possible. None of this story is possible. It's a 판타지 story about creatures that don't actually exist. Within the context of the fantasy, however, this is how it works:
뱀파이어 are physically similar enough to their human origins to pass as humans under some circumstances (like cloudy days). There are many basic differences. They appear to have skin like ours, albeit very fair skin. The skin serves the same general purpose of protecting the body. However, the cells that make up their skin are not pliant like our cells, they are hard and reflective like crystal. A fluid similar to the venom in their mouths works as a lubricant between the cells, which makes movement possible (note: this fluid is very flammable). A fluid similar to the same venom lubricates their eyes so that their eyes can 옮기기 easily in their sockets. (However, they don't produce tears because tears exist to protect the eye from damage, and nothing is going to be able to scratch a vampire's eye.) The lubricant-venom in the eyes and skin is not able to infect a human the way saliva-venom can. Similarly, throughout the vampire's body are many versions of venom-based fluids that retain a marked resemblance to the fluid that was replaced, and function in much the same way and toward the same purpose. Though there is no venom replacement that works precisely like blood, many of the functions of blood are carried on in some form. Also, the nervous system runs in a slightly different but heightened way. Some involuntary reactions, like breathing, continue (in that specific example because 뱀파이어 use the scents in the air much 더 많이 than we do, rather than out of a need for oxygen). Other involuntary reactions, like blinking, don't exist because there is no purpose for them. The normal reactions of arousal are still present in vampires, made possible 의해 venom-related fluids that cause tissues to react similarly as they do to an influx of blood. Like with vampire skin—which looks similar to human skin and has the same basic function—fluids closely related to seminal fluids still exist in male vampires, which carry genetic information and are capable of bonding with a human ovum. This was not a known fact in the vampire world (outside of Joham's personal experimenting) before Nessie, because it's nearly impossible for a vampire to be that near a human and not kill her.
nevermind606 is in the correct answer, It's true. 당신 know that the men's body never ends producing sperm evn if they are vampires. This means all male 뱀파이어 can have sexual relatins with a human woman and she could get pregnant, because the vampire would give his sperm to her.
But what do happens is that female 뱀파이어 can't have children because, as 당신 know, women can procreate for only a period of time. She is borned with a number of eggs, and never will produce more. Those are the eggs for her life. So since she can't produce more, she can't procreate more.