Extract from the article I mentioned above:-
The author Blake Morrison obtained notes from an NSPCC case conference on the Thompson family. "The Thompson report is a series of violent incidents," he reported, "none of them in itself enough to justify the kids being taken into care but the sum of them appalling. The boys, it's said, grew up 'afraid of each other'. They bit, hammered, battered, tortured each other."
The report is full of violent instances, with details of such incidents as Ann taking her third son Philip to the police station after he had threatened his older brother Ian with a knife. Ian, aged 15, subsequently asked to be taken into care and when he was returned home he tried to kill himself by overdosing on painkillers. The notes record that Ann and Philip had also previously taken overdoses.
The Venables household was also fraught but contrastingly so. While Susan and Neil Venables lived in separate houses a mile apart, they tried to bring up their children in a united way - Jon spent Sunday to Thursday with his mum and the rest of the week with his dad. But things were difficult. Jon's brother and sister both had learning difficulties and were being taught in separate special schools, while Jon himself was hyperactive and always playing up. It was Jon Venables, not Robert Thompson, who had a record of violence, having attempted to throttle another boy at school.
In January 1987, the police were called to Susan Venables' home because the children (then seven, five and three) had been left alone for three hours. Case notes observe that her "serious depressive problem" made Venables suicidal.