i would be a dumb ass and not kill any of them just chain them up real good and let them live with me because i love my whole family..and id set trip wires in case they got loose.. I A M A D U M B A S S
Some people won't be able to do it. They will be the ones that end up zeds like their family members. Some will run not wanting to deal witht he thought of having killed their own family and friends. Some will do the right thing. They will end their family members un-life and give them rest. Many people can't do the right thing. Nature dictates that the strongest survive. Strong in mind, body and soul.
A person cable of coldly and precisely execute their entire familly, regardless of whether zombified or not, is not an example of a strong person. That could be called survival of the fittest yes but you are left with only phycotics in that aftermath. Besides nature also dictates protection of your own blood, the selfish gene as it's called.
Truth be told, if we are talking about a full blown apocalyse scenario then you, as a now selfish individual (the only way to survive) it is better to leave and not look back, let your familly walk dead. The burden of killing them will make a mess of you.
They're already dead so it isn't execution. I don't know that I'm capable of cold blooded execution. I hope to never find out. Stopping their undead walk allows dignity and keeps them from making other zeds. It also keeps them from making you into a zed. It is about survival. Psychotics and Sociopaths care nothing for dignity. You do it your way, I'll do it mine.