> Bear in mind that for most of the last hundred-and-something years, the psychological profession has laboured under the blank-slate assumption that human psychology is 100% learned and the human brain is somehow a general-purpose learning machine; in which case the identically of these unevolved blank slates makes perfect sense.

This is a myth. (I'm not sure where it comes from... maybe Steven Pinker?) Psychologists have held all kinds of different beliefs about the relationship between genetics and psychology. Carl Jung, for example, thought we could inherit memories from our ancestors genetically.