Just going to be tossing this in:
@"Shadowborn" do we stick with the thing discussed in the past where it was Gene who approached Jaya, and that animosity between the two of them? Because she cussed out, slapped, and walked away from whoever it was that gave her the abilities, and this might affect the family dynamic - obviously, first and foremost between the two of them, but since Jaya was picked up by, brought into the family by, and clung to Percy, it might affect her as well.
Also, in general she's distant to everyone in the family that isn't Percy, but it's more pronounced with the parents.