Southern Vampire Mysteries Sookie Stackhouse?

I know that Sookie is not telepathic because she's part Fae, that has been made clear several times over, but I still don't know why she is. Someone told me that it was explained in the last book but I haven't gotten around to reading it yet so could someone please explain. I don't care about spoilers. My friends will ruin it for me soon enough anyways. Thanks a billion.