The only reason Amber is averagely good at manipulation is because that is how she survived her entire life, it's the only life skill she has and has ever used ever since she was a child, but she never grew up. People tiptoed around her because she was an orphan as a kid and now they tiptoe because of her weight. She never experienced real life, for the matter of fact.
It's a pretty popular theory that her brain just stopped developing in her pre-teens or teens, I'd like to expand on that.
Metabolic syndrome is a cluster of conditions that occur together, increasing your risk of heart disease, stroke and type 2 diabetes. It usually occurs in obese patients who's fat tends to cluster around the abdominal area. It is also able to develop in children and ends up being more damaging because children's fat distribution is uneven throughout the body and is mostly stored in the stomach. ALR was EXTREMELY obese as a child, I don't remember how much exactly but it for sure was 200+ pounds. Even if she was young, that kind of weight had to have an effect on a developing child.
In this study 49 adolescents with and 62 without MS received high grade evaluations. The study concluded that "Adolescents with MetS showed significantly lower arithmetic, spelling, attention, and mental flexibility and a trend for lower overall intelligence. They also had, in a MetS-dose–related fashion, smaller hippocampal volumes, increased brain cerebrospinal fluid, and reductions of microstructural integrity in major white matter tracts."
These children also tend to be malnourished and just not get enough blood to their heads in general.
Some more things I found:
Metabolic disorders section in
wiki of neurodevelopmental disorders "A non-diabetic fetus can also be subjected to glucose effects if its mother has undetected gestational diabetes. Maternal diabetes causes excessive birth size, making it harder for the infant to pass through the birth canal without injury or it can directly produce early neurodevelopmental deficits. Usually, the neurodevelopmental symptoms will decrease in later childhood. "
It is also very possible that since her parents were druggies it contributed highly to her mental development, I mean addiction is never really good for the brain even if the substance abused is not causing direct damage to it, especially as a child.
I personally just think that she never grew out of the foster home, and although it might sound like a terrible experience I think it was the highlight of her life. She always got what she wanted, could manipulate anyone by pulling her orphan card and engorge herself in food. Everyone has moved on but she is still stuck in that mentality
