There is an ongoing debate in human development between nature and nurture. There are those who believe that people are hard wired by their genetics, predestined to become the next Mother Teresa or Jeffrey Dahmer regardless of our upbringings. Then there are those on the other side of the fence who believe that virtually nothing is certain, and our flaws and successes can be blamed on mommy and daddy.
While the truth lies somewhere in the middle, exactly where in the middle is up for interpretation.
Part of the trouble in answering the question is that our genome is just so stinking complex. Genes on different chromosomes can somehow work together to influence traits while other sequences directly linked to each other don’t at all. However, it has been proven that genetics do play a factor in many human characteristics other than breast cancer and height.
One of these genetically-affected traits is thrill-seeking, and in a new paper published in Psychological Science by Jaime Derringer from the University of Minnesota, Derringer’s team shows that thrill-seeking and other characteristics can be influenced by different mutations to a host of various single nucleotides.
Yes, that’s right. You can blame your addiction to Cedar Point on your family tree.
Thrill-seeking is a partially inherited trait that can be measured by taking a Zuckerman’s Sensation Seeking Scale Form V. This questionnaire rates four subsets of thrill-seeking such as “Boredom Susceptibility” by asking questions like, “When you can predict almost everything a person will do and say, he or she must be a bore.” Other types of questions include the types of parties people enjoy, what kinds of art are aesthetically pleasing and whether or not they’d enjoy jumping out of a plane.
Besides asking people questions, thrill-seeking tendencies also have been linked to alterations of the dopamine system; which is a chemical that carries signals to the brain. Because Derringer knew thrill-seeking is at least partially hereditary and is effected dopamine, she looked for genetic mutations that affect this behavior on genes that control dopamine.
Some genetic mutations are cut and dry; when this string is ABC instead of XYZ, then the person has green eyes. Others are more spread out; when these letters are AMZ instead of ENW, then they’re more likely to develop breast cancer. However, the new study sheds light on just how complicated and unpredictable mutations can be.
The study took the genetic information of 635 individuals who had participated in an addiction study. Derringer looked at 273 individual nucleotides – the individual chemicals represented by the genetic letters in DNA code – and narrowed them down to just 12 that apparently had an effect on thrill-seeking. According to the data, they affect just under four percent of the difference between people in thrill-seeking, which is a lot for a genetic study.
However, how they have an effect is a testament to the mumble jumble that is our genetic code. No single mutation or set of changes seems to make a difference. In fact, one nucleotide changing from an A to a C could have just as much of an affect as that same nucleotide changing from an A to a T.
Whatever the case, theoretically the study could someday lead to a better understanding of what makes some people have addictive personalities and others fly a straight arrow. But that is a long, long ways away, and likely won’t have much to do with this individual study. I just think it’s kind of cool that the human genome is so baffling.