Why I believe at least SOMETHING happened to the family....
The picture of the hallway with the kid with completely white eyes standing there staring at the camera. All the people who investigated the house agreed that there were no children and no one else in the house that night, yet the child shows up clear as day in the picture. In the whole documentary that's the one thing that stood out to me. Danny (and the rest of the family) could be embellishing quite a bit what happened in their time there, but that picture, assuming it wasn't doctored at all, is creepy as hell and suggest at least something was going on with that house.
BARTYOUWANNASEEMYNEWCHAINSAWANDHOCKEYMASK?!?!