I believe it is learnt as what happened in younger life can have an affect on your actions when you are older. I think that if people knew the symptoms then they could help these children so that they don't feel ignored and unwanted and they can make something good of their lives.
Good and Evil are relative to the observer. That which you deem as "good", another may see as "evil". Humans are born as basic neutral sponges and are taught morals, ethics, and good vs evil by their family.
Moving into adult years, that same human will revise and adapt their moral and ethical beliefs based on experience and observation.