Yeah, I've thought about this a lot.
I'd say it could happen, but not like the living dead or anything. I mean, think about it. Just somehow tweak the amygdala (responsible for fear and aggression), screw around with the frontal lobe (planning, judgement, and personality), and BOOM! You've got yourself a homicidal maniac.
So I think it's possible like that, yeah.
Preparedness: I think I'm pretty good here. I've got a pistol, a shotgun, and my fiance and I are going to buy an M4. And I'm a pretty good shot. And my beloved is even better. And he has 3 pistols in addition to all the other stuff. I also have a bug out bag (though it's for natural disasters, not zombies. At least I have one.) He is working on his.
Personality wise, I do what needs to be done. Little emotional bullcrap to get in the way. If I needed to, I could kill someone. Yeah, I'd cry later, but I'd recognize that it needed to be done and I'd do it. On the other hand, I have pretty serious depression, so if things got really bad I might just off myself.
3nodding