I have no patience with the hypothesis occasionally expressed, and often implied, especially in tales written to teach children to be good, that babies are born pretty much alike, and that the sole agencies in creating differences between boy and boy, and man and man, are steady application and moral effort. It is in the most unqualified manner that I object to pretensions of natural equality. The experiences of the nursery, the school, the University, and of professional careers, are a chain of proofs to the contrary.*It seems, from Galton’s quote, that there were already in the Victorian era motives for suppressing facts about heredity. Perhaps the Victorians felt that the concept of innate talent would undermine their ideology that effort was virtuous and would be rewarded.
Galton argues, in passages following the one above, that no amount of effort or training will overcome large differences in innate ability.
* Francis Galton, Hereditary Genius: An Inquiry into its Laws and Consequences, University Press of the Pacific, 2001, p.56, italics added.