Things which catch my eye or make me think - looking for aquamarinegreen, the evidence and the truth of it all.....

Friday, 14 March 2008

The Puzzle of Personality

We don’t just “decide” how to feel about the situations we find ourselves in - our feelings and emotional responses just seem to be there. What is it that shapes our different personalities and behavior patterns?

The scientific view is that the mind is a product of the brain, which gives the illusion of an inner “self”. The brain is organized in part by our genes, which of course were shaped by natural selection. We know that genes account for about 50% of the variation in personality and intelligence (identical twins separated at birth are highly similar; identical twins raised together are more similar than fraternal twins raised together; biological siblings are far more similar than adoptive siblings).

Most people conclude from this that the other 50% must come from the environment. There is actually no evidence for this – it is an assumption that if it’s not hereditary, it must be environmental (50% nature, 50% nurture – good compromise).

However the other discovery, which is just as important, though less well appreciated, is that the twins separated at birth are no more different than the twins who are brought up together. If there was an environmental effect you would expect more similarity in twins raised together. Not so. This is considered by some to be the most important puzzle in the history of psychology. The suggestion is that it is not environmental influences which determine the other 50%!

Steven Pinker in “The Blank Slate” concludes that there are chance events in the wiring of the brain both before and after birth, which could determine the remaining 50% of the variation in personality and intelligence. Sadly such views are so weighted down with political, moral and emotional implications that we hardly dare speak of them. Why can we not embrace this amazing knowledge, and accept that we probably cannot shape our children’s personality and intelligence?