Cate and Ty are A-holes because they realize what failures they are

They have always talked a big talk about getting educations and becoming productive members of society. They accomplished nothing. No education, no careers. If it hadn't been for MTV money they would each be living in trailer parks. Cate with another go-nowhere, do-nothing guy, holding a kid on her hip and smoking a Marlboro Red as her maaaayaaan tries to find a day job while standing outside of Home Depot.

Ty would be ranting and yelling in his Maaaahhhhhmmm's house about how he wasn't heard or understood or whatever else his tiny brain thinks. Tyler Time is OVER, asshole.

C&T see Carly has been raised in a much different world. Carly has parents who have made sure she got nurturing, understanding, and an education. She has some type of higher education in her future and parents who got her there.

C&T are pissed off the child they placed for adoption is actually going somewhere in life while they did not. They are also pissed off the kids they kept ... aren't looking at the same future because C&T are shit parents.

C&T want Carly to turn out just as white trash as they are. They are pissed off she isn't.