Alukah

Sillah and her twin brother Samael learn that vampirism is closer to home than they could ever have expected. It is a hereditary condition complete with medical symptoms that are often explained away by doctors as something mundane rather than what they really indicate. What the twins have inherited is something that has been passed from mother to daughter for generations, typically sparing male progeny.
However, in the case of twins, any males who receive this genetic mutation do so with results even more disastrous than experienced by their female siblings. Tsillah and Samael are struck by the realization that their bodies are changing in ways their peers could never imagine while struggling with the absence of their mother who, having disappeared when they were infants, might have been able to prepare them for the horror that is to come.
Instead, they must face their fate head on and alone. If they do not move fast, they risk losing their humanity to their very real demon sides.