Yes, there are monsters from middle-class backgrounds, people who've apparently had loving and devoted parents, but their childhood might not have been as healthy as it seems. Their parents may have been so wrapped up in their work or otherwise self-absorbed that they never gave their children the attention they needed.
Like 16 year old William Cornick from Leeds, who murdered his teacher in 2014, and came from a respectable middle-class home. His mother was a human resources manager and his father was a council executive. All those who knew him were baffled that he could have done something so dreadful.
But if you look closely at the background of hardened criminals, you often find a history of ill-treatment. Many serial killers are abused - physically, psychologically, sexually - as children by a close family member.
Children can easily be damaged by their home life. Years of poverty and deprivation, squalid housing, or parents with drug or alcohol issues, can leave a child with a deep-rooted bitterness about the unfairness of life, and that can lead to them lashing out in unpredictable ways.
I just can't believe that some people are inherently evil. It seems like a very cynical and negative view that ignores the huge influence of childhood experience on impressionable young brains. I'm sure good-natured children can easily become vicious and destructive if they're exposed to uncaring parents for long enough.
But perhaps I have a slightly rose-tinted outlook that defies reality.