The Blank Slate Theory

One of the oldest and most controversial theories in psychology and philosophy is the theory of the blank slate, or tabula rasa, which argues that people are born with no built-in personality traits or proclivities. Proponents of the theory, which began with the work of Aristotle and was expressed by everyone from St. Thomas Aquinas to the empiricist philosopher John Locke, insisted that all mental content was the result of experience and education. For these thinkers, nothing was instinct or the result of nature. The idea found its most famous expression in psychology in the ideas of Sigmund Freud, whose theories of the unconscious stressed that the elemental aspects of an individual’s personality were constructed by their earliest childhood experiences.
How it was Proven Wrong:
While there’s little doubt that a person’s experiences and learned behaviors have a huge impact on their disposition, it is also now widely accepted that genes and other family traits inherited from birth, along with certain innate instincts, also play a crucial role. This was only proven after years of study that covered the ways in which similar gestures like smiling and certain features of language could be found throughout the world in radically different cultures. Meanwhile, studies of adopted children and twins raised in separate families have come to similar conclusions about the ways certain traits can exist from birth.