"Give me a dozen healthy infants, well-formed, and my own specified world to bring them up in and I'll guarantee to take any one at random and train him to become any type of specialist I might select – doctor, lawyer, artist, merchant-chief and, yes, even beggar-man and thief, regardless of his talents, penchants, tendencies, abilities, vocations, and race of his ancestors."
For many years this blank slate view predominated, on every topic of human nature. Leading to some tragic results occasionally, such as the case of David Reimer in which attempts to socialize him as a girl after a botched circumcision against his will likely contributed to his suicide.
Eventually the evidence became overwhelming that this view was faulty. But more than that, the wishy washy "everything is nature and nurture all mixing together" fallback position was although not explicitly wrong profoundly disingenuous. Who you are is almost entirely contained within your genes, with a minority contribution from enviroment and parents and schooling. Nature won the debate, as profoundly as it was ever possible to win it, and it annoys me seeing equivocation in the discussion of the matter.