Recently a probability chart produced by a Harvard Law School blogger attempted to calculate how probable it is for your father’s sperm to meet your mother’s egg and create you. Basically, he tried to calculate how likely it is if time were to go back to that moment that you would exist.
From his estimates, it is around 1in 400 quadrillion! To put things in perspective, the likelihood of winning the lottery is roughly 1 in 175 million. This means that the probability for a particular sperm and particular egg to meet and create you is far more astronomical! Now then, what if you wanted to trace it back through all of your ancestors, meaning all of your relatives would also have to survive the reproductive age?
Going back to the beginning of life on Earth, the probability of you then existing is 10^2,685.000! Of course these are not exact figures because we cannot actually be sure, but it puts into perspective just how unlikely it is that we all exist!