Ok, so that's an oxymoron, but let me explain. The Grandfather Paradox has to do with time travel. Let's say I figured out a way to travel through time. Where to go!? Well, I was going to visit Gramps anyway. Why not kill two birds with one stone. I might as well meet him in the past.
I could go back to a time before he kept a bedside "teeth cup", and smelled like old beer farts (this would mean traveling WAY back). I figure, just to be safe, I'd go back and visit him before my parents were even born. If I meet him and he doesn't know me then "hey! It's just like last week!" but this time sans Maalox mustache.
So I fire up the time machine and head back to 1943. While I wouldn't actually do this, if I was following the theory of the grandfather paradox, I would have packed my Patricide tools which I would then use on Gramps.
This leads to the paradox. If I killed my grandfather before my parents were born, then i would never have been born. If I had never been born then I couldn't have traveled back in time to kill my own grandfather, in which case I would eventually have been born, grown up, gone back in time, killed him, would never have been born, couldn't have gone back in time... Paradox
What this theory does not take into account is Grandma...
From what I understand, back in the day my grandmother was quite the hot ticket...
who knows what shenanigans she might have gotten into when Grandpa was off killin' nazi's, walking to work with no shoes, or hiding scrap metal metal to benefit the war effort.
Not that I doubt my dear old grandmother's virtue, but how can you be absolutely sure that knocking off grandpa would create a paradox? Those were the days of doctor housecalls, door-to-door salemen, and maytag repairmen... There were a lot of dudes coming in and out of grandma's life (no pun intended).
Soooooo... The Grandfather Paradox makes no sense. It should be the "Grandmother Paradox". The only way to be absolutely sure you create a paradox is by getting rid of Gram... Next week "Milkman Paradox."