Some of the characters don't act their ages.

A lot of the characters are mature, and yet it's like I am reading about a little kid. A lot of the main characters use the term 'mommy and daddy' to refer to their parents when talking about them. I don't know too many teens who still call their parents mommy and daddy.
The twins in Hidden Jewel irritated me. They didn't seem like twelve year old boys at all. They were calling their parents mommy and daddy and I know that most twelve year old boys would be embarrassed to call their parents mommy and daddy. They were also confused about sayings such as "I have butterflies in my stomach." When Pearl is telling them about the human body and getting sick they ask questions a seven year old would ask.
One of them says when an old lady dies: "She was worn out like our tricycles"
And then in the Dawn series after Dawn dies and Christie takes off to look for her father, they treat Jefferson who is nine like he is a child of five. They actually help dress and undress and also help take baths. At the age of nine kids know how to do that stuff.
It just seems like a lot of these characters don't act their ages. I remember being twelve and a lot of the boys my age were a lot more grown up then the way the twins are described. I just think the ghost writer needs to know a bit more about what people are like at certain age groups. I love the books but sometimes it just seems like I am reading about a really young kid.

I totally agree with you.

The majority of the main characters are supposed to be about 15 years old to start with, and they just don't act it. I don't think anybody actually acted like some of these characters at 15, or any age close to that to be honest.