Blank slate, or tabula rasa (which means the same thing) was a philosophical idea of John Locke. It had, like much of philosophy, a history which went as far back as Aristotle, but it was Locke who made it known to our modern world:
Humans, when born, are thought not have mental experience or knowledge, and that everything is learned after they grow. In particular, Locke thought all knowledge came from sense data, and the mind is empty at the beginning. By 'sense data' is meant the process of hearing, seeing, touching etc.
Locke's idea was immediately picked up by others:
Many have held similar views. The founder of behaviourism, John B. Watson (1878–1938):
Throughout the 20th century the influence of evolution and genetics ran against these liberal ideas. Ethology proved that much animal behaviour was inherited, instinctual, (innate and permanent). Konrad Lorenz argued that the aggression so obvious in the history of mankind was a playing out of behaviour which had evolutionary advantage in our past. The field of evolutionary psychology set out to examine the role played by evolution on our mental life. If humans share a common evolutionary history with the other animals, it is likely that we inherit mental traits from our evolution. The human ability to learn a language is inherited, and is of huge practical importance. Very important also (though less obvious) is the way that our unconscious mind helps us get through life. The apparatus which performs that mental activity is certainly inherited. These are some reasons why a number of recent publications have rejected Locke's idea.