Some of the more subtle signs of C.U. children as explained on the top of page 6 are frequent lying for no reason, manipulation, lack remorse/guilt, lack of empathy, and lack humanity. C.U. children do not care whether someone is mad at them or gaining something at the expense of someone else. All they care about is pleasing themselves at the end of the day.
The idea of psychopathy in young children is so controversial among psychologists because like other personality disorders, it is almost impossible to diagnose