In the last week or so, two high-profile newspaper articles have been published, debunking the widespread belief that we can explain our personalities and our behaviors by looking into our genes. As a creativity researcher, I can’t tell you how many times I’ve been asked “So, is there a gene for creativity?” (There isn’t.) And gene mapping companies like 23andme have a booming business. The price to get your DNA analyzed is dropping fast: the going rate is now $99.
Biologists have known for decades that there can’t be one gene for any observable behavior, trait, or ability. Here’s why:
- Single genes are easy for evolution to select for or against.
- So, if there’s a single gene that leads to a behavior or personality that reduces your chance of surviving–let’s say, an anorexia gene that makes you starve, or a psychosis gene that makes you go crazy–evolution would easily select against that gene. Everyone who possessed it would die without having offspring, and the gene would be selected out of the population.
- And if there were a single gene that led to a more successful personality, bigger muscles, sexier body, or a higher ability level, then evolution could easily select for that gene. The individuals who possessed that gene would survive better, and have more offspring. Eventually, everyone without that gene would be pushed out of the population’s gene pool.
- So if there’s a single gene attached to an observable behavior or trait (and there are a tiny few, that’s why I put an asterisk* at the end of my title) it would have to be a trait or behavior that either (a) didn’t substantially affect your survivability–like eye color, or a preference for red wine over white wine, or (b) severely impacted only a tiny percentage of the people who possessed the gene, so that most of them survive just fine, or (c) expressed itself only after childbearing age, so that the gene could still be passed on.
This explains why there’s not a gene for intelligence, or physical strength, or creativity, or leadership. And yet, we all know that some people are more intelligent than others; some are better basketball players than others; some people are definitely sexier than others; and some people are mental basket cases who would have been lion lunch back during evolutionary time. So what accounts for these differences? Not a single gene: instead, whatever biological basis there is for such differences has to be a complicated interaction of hundreds, even thousands, of genes–which evolution has great difficulty selecting for and against. And the rest of the difference between people has to be explained by environment–neonatal development, infancy, childhood, or social and cultural context.
But don’t take my word for it; read these two recent articles by people far more knowledgeable than I am. First is the weekly Wall Street Journal column by Stanford biologist Dr. Robert M. Sapolsky, called “A Height Gene? One for Smarts? Don’t Bet On It.” He writes that recent genome sequencing has found “evidence of the minimal extent to which some trait is ‘in your genes’ and of how relatively unimportant any given gene is.” Even how tall you are: a recent study tried to find the gene for height, and the best they could do was to identify “hundreds of genetic variants in regulating height….the single genetic variant that was most powerfully associated with growth explained just .4% of the variation in growth, and all of the hundreds of identified variants explained only about 10% of the variation, which is not a lot of explanatory power.” So if genes can’t predict a simple physical characteristic like height, then how could they possibly predict a complex trait like personality or intelligence?
Well, it turns out, genes can’t explain such traits. Another recent study, published in the journal Science, tried to find the genetic variants associated with educational attainment–an impressive research project that studied 126,559 subjects. The most predictive single genetic variant accounted for .02% of the variation between individuals, and all of the genetic variants together explained only about 2% of the total variation. The authors conclude that educational attainment involves a complicated interaction of hundreds and thousands of genes. Which we already knew had to be the case; see my four-point explanation above. And now, we have the evidence to back it up.
A second recent article is a review of Jennifer Ouellette’s new book Me, Myself, and Why, by Matthew Hutson. Ouellette’s book is a review of “the science of self” and scans broadly across DNA mapping and other scientific approaches to exploring human differences. Ouelette sends a body sample off to 23andMe, and gets her complete genotype back in the mail. But she ends up disappointed: “Knowing my genotype told me very little about who I am, merely verifying the genetic basis for the traits I already knew I possessed,” she writes.
If our genes can’t explain who we are, what our potential is, and how we think, then how can we better understand ourselves? That’s a beautiful question, and that’s why I chose to become a research psychologist. The answer to our selves is not in our stars, and not our genes. It’s in psychological science.