"For it to happen, for as many generations are there have been human generations, and for as many generations as there has been life, every single one of your ancestors needed to meet exactly the right mate at exactly the right time and to produce one of your ancestors with exactly the right combination of genes. In each generation, the right sperm needed to fertilise the right ovum.
"And if any one of these had been different, you would not exist."
"So there is no explanation needed beyond pure chance because there is actually nothing to explain.
"And it's this huge unlikelihood of you having this chance to experience life which makes you special; not the notion that there was some pre-determined intent to produce you. Had that been so, there would be no wonder in your existence. You would be nothing more than a conjuring trick; easily understood by the simple-minded but nothing more to be said or discovered.
"As it is, your existence is truly wonderful."
I feel like I should say more but in this case....well said.
What could have happened, did. That's what I know.
-- Obert Kimberly "Dreamer" Tatum, from Dan Jenkins' novel, Semi-Tough
In my genetics class I echo this beautiful thought when I discuss genetic variation among humans emphasizing just how unique every new combination of genes is within the universe. Probalistically speaking each one (except identical twins, and they differ considerably in development and hence are also unique) is a brand new, unpredictable thing in the universe. The potential combinations are so vast in number that none have ever existed in the whole past of human evolution, nor will they likely reoccur randomly in the entirety of humanity's future. The ultimate freedom of action and possibility produced by such immense variation for the individual is truly awesome. Mind boggling in the last analysis.