We aren't born vampires, we're chosen. Even if one of our parents, or both are vampires, it is still undetermined whether we, the children, will be blood-suckers as well. We realize now that Vampirism is genetic. In order to become a vampire, you must have the genetic code within your DNA, whether or not you live through the change is why we say you're "chosen". A human strand of DNA has four bases. Adenine forms a base pair with Thymine, while Guanine forms a base pair with Cytosine. If you have vampire genetics, you only have three bases. Instead of forming two pairs, the bases Thymine, Guanine, and Cytosine form a tri-pair.
Now you may be wondering why I say we aren't born vampires when clearly our genetics say differently. Here's the catch, if you are born from a parent or parents that are vampires, you are born human. It isn't until puberty that you find out if you are a "chosen" one or not. During puberty your hormones kick in and if you are "chosen" to become a vampire the hormones will trigger what we call, the week of ascension or sleep ascension. During sleep ascension, everything inside your body shuts down, with the exception of your brain. Within this deep sleep, you will experience seven dreams, one each day. Each day they will become worse in their enitirety, until the seventh day when it will be decided if you will complete the change. On this seventh day, you will be put to the ultimate tests within your mind. If you are going to complete the change, you will simply wake up at the end of the seventh day, and if you won't complete the change, you will die in the seventh dream and simply not wake up. This is why we say we aren't born vampires, we're chosen. We are not given the choice.