We look human, only seem more entrancing to those who are actually human. It's how we draw you in.

Originally we came from a very rare mutated virus, hence why the first of our kind were nearly insane and obsessed with taking blood for life. But now we have learned to calm down and stay mostly hidden.

While vampires do, in fact, exist, the Cullens are not even relatively close to the way we are. First off, we most certainly do not sparkle, and second, our eye color does not change depending on our diet. There are numerous other things, but I care not to sit here and try and explain it.