This might or might not apply to the case of Casey Anthony. It's just something to look at, in general.
The symptoms presented in personality disorders such as psychopathy, narcissistic personality disorder and borderline personality disorder can be caused by a bio-neurological coping mechanism that protects the person from trauma. The symptoms can be the result of the mind shutting down areas of the brain to cope with devastation - particularly during childhood. Perhaps Casey is a victim of severe abuse, as well. That is not to say that she or anyone is not responsible for her/his actions. The question is, "Is she solely responsible?" Hurt people, hurt other people.
The problem is that while they are shut-down and dysfunctional, the neural-pathways are still needed for "normal" human interaction. This factor might apply here.
To reduce the potential occurrence of this particular factor, the question I ask myself is, "How well or not am I interacting with my children and all people? Where might I be hurting myself and others? Am I keeping in the love?" ♥
Thank you for the gift of your time and for your attention to join me in the exploration. ♥
Metaphysical Life Coach & Public Speaker