Existence
This is going to sound like one of Imsohooood's "I've been thinking" threads, but I was just pondering, if your parents had never met, would you have been born to someone else? Was the person that is you destined to be born, or is it all just chance? Also, if you had been born to someone else, perhaps on other side of the world, how would that have affected you and would you be a different person today? I don't know how I got off on this subject...
Chance.
If your parents had never met, you would not be born.
Instead, another human with its own traits would have.
I agree with Endrit, its all chance.