I've got no remorse period when it comes to potential threats to my loved ones. You kill the whole family to one) make sure that the bad genes, raising, etc doesn't get passed on and more importantly two) to make the punishment of the crime carry such weight that few would try it. As we all know in America prison is soft on people and three) you make sure that no one is left to retaliate against you. If the cops and courts won't protect the people they are sworn to serve we should take matters into our own hands. Why should our tax dollars go to protect and coddle those that would harm our families? Yeah it sounds draconian but its time to actually start punishing the monsters in our society rather than give them a slap on the wrist.
Why does that have to be genetic or the parents fault? What if the person acts that way because they were abused themselves, not by a family member but someone else the trusted. It could have been by a coach, teacher, boy scout leader, religious figure, etc...all of those examples have happened recently and yet the family wasn't at fault for any of them.