Are You a Risk Taker?

Among the groups representing three levels of risk-taking, there were no significant differences on neuroticism-anxiety or activity, suggesting these traits play an insignificant role in risk-taking behavior.

There were, however, notable links between other personality traits and specific kinds of risky behavior. Heavy drinking was associated with all three of the personality traits related to general risk-taking tendency: impulsive sensation-seeking, aggression-hostility and sociability.

But smoking and drug use beyond marijuana were related only to impulsive sensation-seeking and aggression. That finding is interesting because in a previous study we found that the same two traits were also higher among prostitutes than among a control group. The combination of impulsive sensation-seeking and aggression was also related to antisocial personality disorder among male prisoners and to level of cocaine abuse.

Previous research has shown that the use of illegal drugs, even of marijuana, relates to a higher degree of sensation-seeking than is found among those who use only alcohol. The step from legal drugs (tobacco and alcohol) to illegal ones is one taken only by the higher sensation-seekers. The illegal drugs provide more novel and intense sensations and experience at the cost of greater legal and social risks.

In our study, as well as in others, men proved higher risk-takers than women. They also scored higher on impulsive sensation-seeking than women. When we analyzed the gender difference in risk-taking we found that it was entirely a function of the difference between men and women on impulsive sensation-seeking. This is only one of several pieces of evidence suggesting that impulsive sensation-seeking is a basic personality dimension.

Humans are a risk-taking species. Our ancestor Homo sapiens originated in East Africa, and within the relatively short span of 100,000 years or less spread over the entire globe. It turns out that explorativeness may be the key to the survival of the species.

The hunting of large and dangerous game by men required a type of thrill- and adventure-seeking that also contributes to the success of the human race. Over the millennia, men also found in combat and war an outlet for their need for adventure.

Mating, too, was a dangerous game that required risk-taking. The innate incest taboo drove men to seek mates outside their small groups, sometimes from unfriendly groups.

The fact that a trait like sensation-seeking characterizes our species does not mean that individuals don't differ in the degree to which they have that trait. Genetic assortment may maintain variation in a trait like sensation-seeking, which is most adaptive when it is in the middle range: Too much risk-taking leads to an early death, too little to stagnation.

Studies of the heritability of sensation-seeking in humans have used classical twin-comparison methods. Comparisons of identical and fraternal twins in which both siblings were raised in the same families show that sensation-seeking is about 60% genetic. That is a high degree of heritability for a personality trait; most range from 30% to 50%.

A study of identical and fraternal twins separated at birth and adopted into different families showed the same heritability. It also indicated that the environmental contribution to sensation-seeking (accounting for 40% of the trait, or less) is due not to the shared family environment but to the environment outside of the home, such as friends and accidental life experiences.

If children resemble parents or siblings in sensation-seeking, it is probably due to shared genes rather than the influence of the family. Friends and others outside of the home may provide behavioral models and reinforce the disposition carried in the genes.

Genes play yet another role in risk-taking: They influence two other personality traits associated with general risk-taking, including the traits of aggression, or its obverse, agreeableness, and for sociability, the main component of extroversion.

Molecular genetics has made it possible to identify major genes influencing personality and forms of psychopathology. A group of scientists in Israel were the first to find an association between novelty-seeking (a trait very highly correlated with impulsive sensation-seeking) and a gene that codes for a class of dopamine receptor, the dopamine receptor-4 (DRD4) gene.

Dopamine is an important brain neurotransmitter, active in pathways related to the brain's intrinsic reward and pleasure centers. It responds to stress, and enables people not only to see rewards but to take action to move toward them.

Two major forms of the dopamine receptor-4 gene exist, a long and a short version of the same base DNA sequences. The long form is found in a preponderance of those individuals who are high in novelty-(sensation-) seeking. The same form of the gene is found in a high proportion of opiate drug abusers, a high sensation-seeking group.