There are no bad children — only bad parents. This has long been the mantra of child experts. After all, studies have shown that offspring of the violent and abusive often turn out to be highly troubled adults.
But what if a child is born into a loving, caring home and still goes off the rails? And what if the child's siblings, who have been raised in the same loving household, have turned out fine, whose fault is it then?
Astonishingly, some psychiatrists accept that previous thinking was flawed and that some children, through no fault of the parents, are bad seeds. In other words, they are born bad.
Gloria Harding is relieved to learn of this new theory after years of questioning her parenting skills when her once promising son became a violent and aggressive.
The low point came when Gloria, a retired marketing consultant, had to take refuge in her own house while Bobby, then 18, screamed abuse at her as he systematically smashed up the five-bedroom family home in Walton-on-Thames, Surrey.
He had been brought up with every possible advantage but Gloria was at her wits' end over her son. The happy, sweet-natured boy who had shown such early promise had grown into a teenager who was completely out of control.
"I thought I must have been a terrible mother but the truth was that Bobby was loved, praised and encouraged, as was his sister." Gloria lives with her husband Trevor (Bobby's stepfather) in the £1.5 million (Dh8.4 million) house in which Bobby was brought up.
Her son, meanwhile, is 27 and living in residential care after a series of violent and distressing episodes that left Gloria and Trevor unable to have him at home.
By comparison, his 31-year-old sister is a loving, responsible parent. So was Bobby born bad?
According to psychiatrist Dr Richard Friedman admitted that his profession is beginning to accept that some children are "toxic".
"For years, mental health professionals were trained to see children as mere products of their environment who were intrinsically good unless influenced otherwise; where there is chronic bad behaviour, there must be a bad parent behind it," he says.
"Yet the fact remains that perfectly decent parents can produce toxic children."
Certainly, Gloria can't identify any reason why Bobby should have become so violent.
"He was a lovely child. I sent him to a private prep school and our problems began," she says.
"He became disruptive in class and struggled to learn. I feel he was dyslexic — but his behaviour exceeded this problem.
"I took him out of private school and put him into a state school, where they were willing to get a statement of special needs for him — his private school didn't want to know and I felt isolated, as if it was my fault. Meanwhile, his sister excelled at the same school."
Gloria was working full-time and employed a nanny to help care for her children. She and Bobby's father divorced when he was 8 and, a year later, she married Trevor, who has been a consistent and loving father figure to Bobby.
"We weren't overly strict with him and he was brought up in a caring home. He had everything he wanted," Gloria says. "We had lovely holidays, he was a great skier and scuba-diver. Yet there was something wrong within him. There was so much anger inside him."
Gloria struggled to cope. "We had to keep every door in the house locked. He would punch holes in his bedroom walls, scream and break things," she says.
"He once threw all the contents of his bedroom out of the window. I became terrified of him. In the end I called social services and the police because I feared for my safety after he threatened me with a screwdriver."
Bobby was professionally assessed and ruled not to be mentally ill but a teenager with "behavioural problems". Events culminated with Bobby stealing his mother's Jaguar XK8 and wrap ping it round a tree.
Over the next year he was charged with criminal damage and sent to Feltham Young Offenders Prison in West London. "I will never stop loving him and I will never desert him but I fear so much for his future. I am tormented by the thought that maybe it is all my fault," Gloria says.
British child psychologist Dr Pat Spungin says: "There will always be children who are much more difficult to parent than others. While I am reluctant to label children bad seeds, I think some children are born with much less susceptibility to influence.
"Psychologists recognise that there are temperamental differences in babies from birth. The nature-versus-nurture argument will always continue but some children are born with less empathy and understanding of people. They care little about the consequences of their actions and the effects on other people."
George and Nicole Douglas, 10-year-old twins, were born with every possible advantage. Their parents, Doug, 55, and Sandra, 49, dote on them and work hard to give them the best in life.
There is a swimming pool in the garden, holidays abroad, endless treats and new clothes — yet they have often made their parents' lives intolerable.
Young and furious
Doug says: "I can only think we have given them too much. They are much better now but when they were younger we would be covered in bruises. They shouted, swore, kicked and threw things at us," he says.
"They're bright and good at sports. I just sometimes feel I don't know them. They are perfect at school, then they come home and the trouble starts."
However, the situation is getting better and he is trying to put his foot down more.
"But where does this anger come from? Why do they behave like this towards us?"
Dr Friedman says: "Not everyone is going to turn out to be brilliant — any more than everyone will turn out to be nice and loving.
"And that is not necessarily because of parental failure or an impoverished environment. It is because everyday character traits, like all human behaviour, is hard-wired. Genetic components cannot be moulded by the best environment, let alone the best psychotherapists.
"For better or worse, parents have limited power to influence their children. That is why they should not be so fast to take all the blame — or credit — for everything that their child becomes."
For parents like Gloria, the removal of this stigma is a great relief.
"I will never give up on Bobby, he is still my baby," she says. "But I have accepted that his behaviour is not my fault. I've spent too long agonising as to what I could, or should not, have done.