They care for the evil one more since he is younger, they spoil him and does not teach him the lessons they taught his older brother. It is as if they are experimenting with parenting styles. Like the kid is "special." and by special i think it would be either mentally retarded or a sociopath. Which is why they give him all that freedom to be a little dick to everybody.
A family of 5 big roachs under the sink when you were looking for something happen to see them and they all scitter/scatter while one run toward you up your leg. Just Uggh. *Shiver*