I've read a e-book about this recently which has stayed with me (Night Monsters by Lauren White). I suppose it uses the idea that humans are like some other animals - if their nest is disturbed (divorce, financial problems etc) they might kill their young. And it also hints at the kind of perverse love that a suicidal parent in this situation might have because they actually believe that the best way to "take care" of their child if they are are going to commit suicide is to kill them. I feel sorry for the kids. They don't get to choose usually and the terror they must go through knowing a trusted parent is killing them was be awful. In the book I read they don't go through with it but it seems a strange phenomena in our society - I've seen more and more of it in the papers. I wondered what other parents thought about this rather taboo subject.