I hate killing anything but no one likes flies in the house. I killed one a few months back with the flick of a tea towel and felt bad for about 5 minutes. I rationalised that they spread germs so it had to go. That's about the level of how a psychopath views his/her victims. They don't have to enjoy killing, they may even hate it, but if it's a means to an end - the victim has to go and they can always rationalise it.
Mums crazy so better off dead
Sisters even more crazy so better off dead
Dad has to put up with crazy mum and sister so better off dead
Twins have my crazy sister to raise them so better off dead
I can run farm better by myself anyway.
Jeremy's rationalisation in a nut shell