It´s a really sad story.
I agree Alias. The issues and effect of adoption are far more complex than most people comprehend, adopted children often have complicated psychological issues which need sensitive handling and understanding. Back in the 1980s no one had a clue about all this, in fact there was very little understanding about the psychological damage to children from all kinds of adult behaviour.
I believe if JB was guilty the whole family were victims of ignorance which was not consciously of their own making, imagine the total abandonment a young child must feel who has already been abandoned by their natural mother ie. The Primal Wound, who no doubt had attachment problems and confusion to be sent far from the security of their home to a strange and inhospitable school. The adoptive parents were no doubt unaware of these issues because they were never encouraged to know or understand and in turn the loosely named Social Workers were often unaware, uninvolved and shockingly uncaring in my experience when working in that area in the late 60s.
This is my opinion, not an accusation towards anyone but in my eyes a tragedy which was repeated many times, whether it was responsible for JB killing or not, whether he killed or not is debate able and why the forum exists but however you look at it, it is a massive tragedy IMO.