I'm not really versed on the White Wolf mythos, but I think the origin of vampires in that RPG system is Cain of Cain and Abel. He was cursed by God to wander the earth forever in darkness, and any of his spawn would carry the same curse.
Yeah, pretty much. When Cain sacrificed the blood of his brother, God placed a mark upon him and banished him from mankind to the land of Nod. However while being pursued by Angels he came across Lilith (who has her own mythos) and learned to wrap himself in darkness. From here Cain observed mankind in its weakness, and decided to build the First City of Enoch where Cain no longer had to hide, and sired 3 "sons," the Second Generation or Antediluvians which were destroyed (or were they? another story...) in The Flood. Cain escaped and built the Second City and sired The Thirteen, or the 3rd gen, which were the forefathers of the clans. With each generation, the mark of Cain diluted and their powers diminished, and the 13 warred with each other over what they did have. Although the blood of Cain was diluted, they still held terrible forces and the war between them was terrible. Cain got pissed at his childe, and prophesied Gehenna, or the end of the world for the vampires, and wandered off into the night promising that the final judgment of his offspring would be held by him and not by God, and that the children of Seth (Cains other still human brother) would one day no longer be afraid of them and force the vampires into hiding. The 13 laughed, and went back to their wars once Cain left. About this time, the children of Seth Built Constantinople, and the wars between the 13 brought about its destruction. As Constantinople burned, the children of Seth turned on their masters. The 13 realizing that Cain's prophesy might hold some truth, fled into hiding and continue to live in the darkness until Cain comes again to pass his judgment among them.
Been awhile since I have read any of the White Wolf stuff, but i enjoyed the hell out of it back when I had the time to...
EDIT: Oh yeah, all that scared of garlic, and can only come in if invited is BS in the White Wolf World, they are just stories invented by the children of Seth once the vampires went into hiding. Although sunlight and fire do deal aggravated damage which is pretty nasty... As far as holy relics, they only work against vampires whose "Road" or "alignment" in D&D is evil. There are vampires hiding out in the Clergy (several of the Popes are supposed vampires) that are quite comfortable with holy relics.
I really like WW much better than D&D, because you can coincide it with actual history when telling your stories, and just put a little spin on it