Q: If a man dies before his son is born, is he still a grandfather?
A: Ah, you're thinking about that old chestnut, eh? Well, let us consult the ancient tome of Temporal Logic.
According to our calculations, the answer is... it depends.
But don't worry, it's not as complicated as it sounds. Unless you're a time traveler, in which case, it's a whole other can of worms.