Confidence--Partly a Matter of Genetics
Some people are born with the belief that they are masters of their own lives. Others feel that they are at the mercy of fate.
New research shows that some of those feelings are in the genes.
Psychologists long have known that people confident in their ability to control their destinies are more likely to adjust well to growing old than others.
Two researchers who questioned hundreds of Swedish twins report that such confidence, or lack of it, is partly genetic and partly drawn from experience.
They also found that the belief in blind luck--that coincidence plays a big role in life--is something learned and has nothing to do with heredity.
The research was conducted at the Karolinska Institute, which annually awards the Nobel Prize for medicine, by Karolinska’s Nancy Pedersen and Margaret Gatz, a psychology professor at the University of Southern California. Their results recently were published in the United States in the Journal of Gerontology.
The study of twins, who have identical or similar genes, eliminates genetics as the explanation of differences, said Richard J. Rose, professor of psychology and medical genetics at Indiana University. Variances in twins must then be attributed to their distinct environment and experiences.
The result of the Gatz-Pedersen study “is consistent with other world literature on the subject” but has the added importance of being based on a far larger and more representative sample than previous research, Rose said.
“The belief in your ability to control your life direction, or the belief in your own competence, is 30% something you are born with,” said Gatz, interviewed during a consultation visit to Sweden.
People who are confident of their ability to control their lives have an “internal locus of control” and a better chance of being well-adjusted in old age, said Pedersen.
An “external locus of control”--believing that outside forces determine the course of life--has been linked to depression in later years, she said.
“This is one of the windows on the aging process,” said Pedersen, who has published a series of studies on the genetics of personality traits based on interviews with twins. The study on life control involved 554 pairs of twins.
“We are trying to understand what makes people different. What makes some people age gracefully and others have a more difficult time?” she said. “Whether people feel independent is an important standard for service institutions and how they treat the elderly.”
The study showed that while people have an inborn predilection toward independence and self-confidence, about 70% of this personality trait is affected by a person’s environment and experiences.
Pedersen’s studies, with various collaborators, probe the aging process by comparing sets of twins, identical and fraternal, many of whom were separated at an early age.
The subjects were drawn from a roster first compiled about 30 years ago registering all twins born in Sweden since 1886. The complete list, which was extended in 1971, has 95,000 sets of twins.
Rose said the registry, based on the whole population, is “an unusually powerful tool.” U.S. researchers have nothing comparable and normally rely on twins who respond to advertisements.
Karolinska professor Anders Ahlbom, who runs the registry, said 80% to 85% of twins typically respond to questionnaires sent by researchers.
Pedersen said that studies of twins who were reared separately but have identical or nearly identical genes, compared to twins reared together, can yield a unique measure of nature-vs.-nurture in human development.
Earlier research by Pedersen showed that a variety of other characteristics are 30% to 40% determined by a person’s genetic makeup, including many of those traits that make up what has become known as Type A behavior.
The Type A person--the hard-driving worker who brings home his work from the office, eats too fast, keeps his foot on the clutch at traffic lights and makes a point of being on time--has been found to have a higher risk of heart disease before age 65.
