Who Can You Blame for Your Personality?
What is Personality?
Personality seems so intangible – and is expressed through so many little behaviors and habits – that it’s hard to believe that it is carried within our genes. And yet, studies have consistently shown that personality is heritable. About 50 percent of variation in personality can be attributed to our genes.
Double the Trouble
We can see this phenomenon in that gold mine of scientific research: Twin Studies. Identical twin (with identical genetic profiles) are much more similar to each other in personality than fraternal twins are. In fact, the personalities of identical twins raised in separate households are highly correlated. Their counterparts – adopted children (with very different profiles) who are raised together show essentially no personality correlation with their sibling or adoptive parents.
If 50 percent of personality is heritable, 50 percent still comes from the environment. Yet, parenting and the household environment seem to have little impact on personality (as seen by the differences among adopted children). Researchers haven’t yet pinpointed the factors that account for the other 50 percent.
Did you know . . .
Upbringing does affect religious and political beliefs as well as health habits. Children are likely to reflect their parent’s attitudes, as well as their smoking and drinking habits.
Neuroscience and Your Personality
The famous and often quoted case of ill-fated railroad worker Phineas Gage, whose personality dramatically changed after an injury to the front of his brain, was an early indicator that personality and brain structure are linked. Scientists now know that the prefrontal cortex is responsible for planning and impulse control.
People who are high in neuroticism have easily activated limbic systems (brain structures under the cerebrum that are associated with emotion). Levels of neurotransmitters – chemicals that carry information across brain cells – also seem to vary according to personality. Studies show that the enzyme monoamine oxidase (MAO), which breaks down neurotransmitters is lower than average in people with sensation seeking personalities. It may be that the wild partiers and fast drivers have neurotransmitter levels that are simply too high for safety.