half-blood

Okay so I'm in a bit of a situation.. I don't look like anybody in my family, I'm really white and I can't tan.

I can eat normal food but I crave blood. I barely ever get sick. My "grandparents" call me a vampire...

I need to know if it is possible to be half vampire half human.. Please i really need answers and I'd what to do... I can't reveal my identity or anything but.. Idk.... please help