I'm a great fan of Scott Peck. He describes the narcissisic/psychopathic parent perfectly.
Like the heartbreaking story of the lad who got a shootgun as a present for his birthday (he'd asked for a tennis racket) Scott describes the parents as 'evil' and he is correct.
They were evil ie: without empathy, therefore very destructive parents so much so they caused their other son to despair so much he shot himself.
There are people such as psychopaths who are evil, without conscience.
Without the ability to feel others pain there is no brake on behaviour.
IMO truth is some people are born unable to process empathy a malfuntion in the brain, a fault in the Amagala were emotions are processed. The brain is ultimely just another organ and like any other can be faulty and malfuntion.
Psychopaths brains look very different compared a non psychopaths.

Two of my favorite books 'A Road Less Travelled' and 'The People Of The Lie'
True, half way through 'The People Of The Lie' he loses the plot and gets all religious but other than that he's right (I'm not religious by the way)

This: Further, he says that mental illness stems from this missing or defective love in childhood. (Scott Peck)
He is correct. No love in childhood is one of the biggest causes of mental ill health. Thats what caused mine anyway. No one gave a ####

I don't know about all the 're-parenting' therapy stuff as I've never had therapy, rare to have a therapist in the UK though if I'd had a good one as a young teen I think it would have helped.