There are millions, if not billions or trillions, of possible permutations that 20,000 human genes can arrive at during the development of the fetus in the human womb.
Such is the number of permutations. overwhelmingly greater than the number of people on earth — seven billion so far — that it means each of us has a unique personality. Such a personality, modified only by unique indoctrination in childhood, is launched at the time of puberty and remains ours for life.
If Herodatus (484 – 425BC) had included the above in his “circumstances” then he would have been correct when he wrote: “Circumstances rule men, men do not rule circumstances.” Histories.