"What is it with YA novel heroines disliking their parents?"

Because they get in the way of their awesome adventures, I guess. Plus it's totally lame to explain about the secret, magical stuff to grown-ups!

(I really need to read the Percy Jackson series, incidentally. From what I understand, Percy's mother actually DOES know about the crazy stuff her son is involved in, and at one point helps out in a fight with a gun she stole from a policeman)