'As a member of the human species, I have a particular genetic identity. There are about 30,000 active genes in the human genome. Each of these genes has at least two variants, or 'alleles'. So the number of genetically distinct identities the genome can encode is at least 2 raised to the thirty-thousandth power which roughly equals the number 1 followed by 10,000 zeros. That's the number of potential people allowed by the structure of our DNA. And how many of those potential people have actually existed? It is estimated that about 40 billion humans have been born since the emergence of our species. Let's round the number up to 100 billion, just to be on the conservative side. This means that the fraction of genetically possible humans who have been born is less than 0.00000...000001 (insert about 9,979 extra zeroes in the gap). The overwhelming majority of the genetically possible humans are unborn specters. Such is the fantastic lottery that I - and you- had to win in order to shimmer on to this scene. This is contingency with a vengeance.'
Jim Holt, 2012, Why does the world exist? p. 254
