I believe a great deal to do with it is that these folks should not have had children to begin with. I feel if you can't financially, emotionally, educationally, psychologically, afford to bring up a child, if you're under the age of 25, if you don't have a back up person to help you out with taking care of a child, if you don't have skills that allow you to work, hold down a job, support the child fully, then you should not be breeding.
I Chose not to have a child. I was in college when I found out I was pregnant at age 19. It was an 'accident' and I wasn't planning on it. At the time, my fiancee was not ready for a child, either. I was sad, but decided to have an abortion. Yes, sometimes I am very sad about it. But I knew I would not want to be a burden to others, or unable to support myself and a child. Some folks may disagree with this stance, but I felt it was being responsible.
I feel that people who have children that can't take care of them are a big part of why this happens. Dad did look very capable at one time, but the birth mom said he could be controlling at times. I would bet a dollar that drugs are involved in this case. Step mom had a good education-I would have expected more from her. I don't understand this sort of cold, unfeeling psychopathism that killed these children. I just don't understand.