Note 51 — Chapter V

In strict accuracy, the law of ancestral inheritance must be described as giving means of determining the probable deviation of any individual from the mean of his own generation, when the deviations of some or all of his ancestry from the types of their respective generations are known. It presupposes (1) no assortative mating, (2) no inbreeding and (3) no selection. Galton's own formula, which supposed that the parents contributed ½, the grandparents ¼, the great-grandparents ⅛, the next generation ⅟16, and so on, is of value now only historically, or to illustrate to a layman the fact that he inherits from his whole ancestry, not from his parents alone.