Experts say a California couple accused of beating, shackling and abusing their 13 children may have used starvation as a weapon to control them.
The parents, who were charged with multiple counts of torture, child abuse and false imprisonment, gave little food to their children, ranging in age from two to 29 years old, according to prosecutors, who said the abuse may have gone on for years.
The couple even taunted their offspring by displaying desserts that they were not allowed to eat.
Although their motives were still unclear, the couple may have denied the children food as a way to weaken them and assert power.
The children were also shackled and beaten for perceived minor infractions, authorities said.
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The 17-year-old girl who escaped from the family's house in Perris, California this week to call the police and reveal the alleged abuse, was so emaciated she appeared to be only 10, authorities said.
"You're tired, your ability to stand up for yourself is at its limits," said Dr Roy Lubit, a New York-based child psychiatrist with expertise in post-traumatic stress disorder.
David Turpin, a 57-year-old computer engineer, and his homemaker wife Louise, 49, each pleaded not guilty during an initial court appearance on Thursday.
The father was also charged with sexually abusing one of his daughters.
Dr Lubit said that starving a child showed premeditation when compared with someone who lashes out and strikes his or her victim in a spasm of rage.
"Hitting comes from angry outbursts, where with starving it's a prolonged period of wanting to domineer, be in control. It's a power trip," he said.
Prosecutors said the Turpins would buy food for themselves, leaving apple and pumpkin pies on the kitchen counter but forbidding their children to eat it.
Experts say the siblings would likely be left with permanent physical and emotional damage, such as anxiety and depression, as well as issues around food.
"When the brain is starved of proteins and other building blocks, brain development is going to be impacted," Dr Richard Pan, a paediatrician who is a Democratic state senator from the Sacramento area, said.
The brain can be smaller than normal, and if typical developmental milestones are missed due to starvation, they cannot readily be made up later, he said.
As the body struggles to protect the heart and brain, it essentially consumes other organs and even bones, said Dr Dean Blumberg, associate professor of paediatrics at the University of California, Davis Children's Hospital in Sacramento.
Growth is stunted and long-term anaemia and other nutritional deficiencies can lead to a drop in IQ as well, he said.
On Thursday, prosecutors said the siblings were severely malnourished, specifically having suffered muscle wasting, and some had suffered cognitive impairment and nerve damage as a result of the prolonged abuse.