You are one of seven billion people living on Earth at this very moment and you one of the hundred billion homo sapiens to ever have lived here over the course of history. That in itself is pretty amazing because the probability of you existing at all is incredibly low. In most cases for you to be alive your parents had to meet assuming that your mother could meet, let’s say one new person a day during her prime dating years, she would have met around 10,000 people. Which in her time was about 0.00025% of the world’s population but because of geographical reasons, if we limit her available bachelors to about 5% of the population, she had about a 1 in 20,000 chance of meeting your dad.
Those are the odds of just them meeting! For them to have to talk to each other (although not necessary), then go on a date (although not necessary), and eventually conceive a child. The chance that combination of a sperm cell and egg turns out to be you in inconceivably small.
Your mother has about 300,000 eggs left by the time she reached puberty and will only release around 300 of them. On the other hand, men produce billions of sperm cells in their lifetimes, any of which could reach that egg.
Feeling pretty rare yet or slightly weirded out?
Keep in mind you existing doesn’t just depend on your parents, it depends on your parent’s parents and their parents and their parents… and so on. If you want to get into the physics of life existing at all we could get into the electric charge, the gravitational constant, and even the dimension of space and time…. because if anyone of these were even slightly different incredibly important atoms like carbon would either be too unstable the electrons would collapse into the nucleus. And if there are no carbon macronutrients, like proteins, lipids, carbohydrates, and nucleic acids… you would not exist.