Wow! read the last sentence of this partial article.
The four types of family annihilator
Examining all the cases led to the identification of four distinct characteristics that drove the murderer, which helps to dismantle the common myth that family killings are motivated either by "revenge" or "altruism".
Self-righteous killers hold the mother responsible for the breakdown of the family and will often call her before to explain what he is about to do. Disappointed killers believe their family has let them down, and the killing could be sparked by something like children not choosing to follow religious customs. Anomic killers see the family as a symbol of their own economic success, but if they suffer some kind of economic failure -- bankruptcy, for example -- the family no longer serves this function. Paranoid killers are often motivated by a desire to protect their family from a perceived threat, such as having children taken away by social services.