This is Why

Because I think that every bit of this behavior can be explained by illness and injury and dental problems and the resulting constant immune activity that shuts down the frontal cortex.
There's a reason these kids don't care about punishment.
Their epithelium isn't functioning. Their facial nerves are disabled.  They can't feel pain.

When Your Child Is a Psychopath
The condition has long been considered untreatable. Experts can spot it in a child as young as 3 or 4. But a new clinical approach offers hope.

Yes, it's amazing what a little nutrition and hygiene and sleep will do for a bag of nerves and skin.