Looking at the World Through a Genetic Lens

There is a general understanding pervading science and, by extension, the general public, that human beings are largely guided by genetics. For some simple things, this seems obvious. For example, eye color can generally be mapped out as directly corresponding to genetic expectations. Sickle Cell Anemia and Muscular Dystrophy are examples of clear, genetically caused diseases, usually involving one “bad” gene. Most such definitive genetic traits have been mapped out and we have some understanding of their cause. It’s not what I want to discuss here when talking about genetic studies. I’m referring instead to the vast majority of genetic studies these days, that are not looking for such a definitive cause to the trait in question.

For example, height and body weight don’t have a single gene that directly causes a person to be tall or heavy, but we do see a sort of trend when considering that, for example, tall people tend to have taller children, so there is an assumption that this is related to genes in some unknown way. Taking it down another level, there are diseases that appear to run in families, like diabetes, or coronary artery disease, or cancer. Implied is that there is some more complicated way in which people might or might not inherit these diseases, or be at a greater risk for them, due to inherited genes. Although the hard evidence for this is more scanty than one might expect, I generally don’t take issue with the assumption that such physical traits have a genetic component. Where I do take issue is when this same assumption is applied to aspects of a person’s personality, intelligence, or mental disorders such as ADHD, depression and schizophrenia. This is my personal obsession and quixotic battle, and I wish to try to explain it without using a lot of technical jargon, as I think it is an important issue not just for scientists, but for all people. So let me elaborate:

I’m sure anyone reading this has seen news stories with headlines like, “Genes for Bipolar Disorder Discovered,” or “Depression: It’s in Your Genes.” The impression given is that this issue has been decided and the debate is over. Perhaps, based on what you’ve read, or even your personal experiences, you have formulated opinions on this subject. Generally, the debate is one of nature versus nurture, with the implication that nature has won out over nurture. I think this is a rather tired debate and excludes other possible aspects of human beings and the human condition that are considered too far out of accepted discourse, at least among the scientific community. I would ask the reader to consider the possibility that we have far less knowledge of human nature than we are led to believe. My purpose, however, is not to convince you of which should win out in a nature versus nurture versus other debate, but only to plant a little bit of doubt or skepticism about what is currently being sold as the truth as we know it. This requires me to talk a little about the genetic studies I alluded to above.

Genetic studies, whether for physical traits like height and weight, breast cancer, or mental traits, are all done in much the same way. We have a process that looks at many thousands of genes that make up our DNA, and can recognize small differences between individuals. The idea is to determine whether a certain group of people (heavy, smart, congenial, bald, etc.) have more of a preponderance of these slight genetic variants. This idea is probably familiar to most people now, as it is the same basic principle used for commercial genetic sites like Ancestry.com and 23andMe.com. No two people have the same genetic code (except for identical twins), but because genes often change slightly over time, people of different ethnicities and geographic locations will tend to accumulate some of the same genetic differences as others within that same group. This allows us to make educated guesses as to someone’s ethnic and geographic background. It might be that some of these genetic variations actually convey some differences in people, such as skin color in a particular group, but probably the majority of such genetic variations serve more as markers and don’t necessarily function differently than those of people of other ethnicities. This is an important point and is key to understanding the limitations of genetic studies. It is generally described as the difference between “correlation” and “causality.” To give an (often used) example, if someone did a cross-cultural, genetic study of people who prefer to eat with chopsticks versus people who prefer to eat with a fork, we are going to find a lot of genetic variations that would correlate to chopstick preference. They would likely be similar to the genetic variations that Ancestry.com would find for people from many Asian countries or of Asian descent. Here we have a “correlation,” but obviously, this is cultural and geographic, and none of these genetic variants are “causal”, in the sense that they determine a preference and make someone want to eat with chopsticks. This is the crux of the problem with genetic studies of any traits. There are always potential areas for these kinds of correlations that aren’t really causal, albeit not always as obvious as this chopstick example.

Thus, when a genetic study is performed for something like a person’s tested IQ, one might find several genetic variations that seem to correlate to high IQ test results. However, if you want to say that these are directly related to a person’s IQ (causal), then, at some point, you would need to demonstrate how this or that genetic variant correlated to IQ works differently than the “usual” genes for those without high IQ test scores. To date, that hasn’t happened, not only for IQ, but for any mental disorder or personality trait. None at all. In fact, even for genetic studies of physical traits like height or disease susceptibility, there has been only a slight bit of success. The research scientists tend to gloss over this fact in a couple of ways. First, they might claim that many of the genetic correlations they found are somehow related to a specific brain function, suggesting they might be involved in mental traits. However, these relationships are quite nebulous and we have the added problem that each study seems to find entirely different genetic variants that have different proposed functions. Researchers are generally unable to get the same results when they repeat the genetic study with a different group of people. This is an important aspect of science because replication of the previous experiment is essential. The inability to do so, has led to what is called a “replication crisis” in the field. It’s a serious issue, since it calls any results into question if you can’t repeat the experiment.

Secondly, they will often cite past twin studies. These studies purport to show that twins often have similar characteristics, which it is presumed are related to their identical genes. There is some debate around twin studies, which I won’t go into detail about here (other than to say that most of us are not twins). In any case, whatever is demonstrated in twin studies, they do not give legitimacy to the results of unrelated genetic studies (for anyone who is interested in the twin issue, I strongly recommend the recent, riveting documentary, “Three Perfect Strangers”).

To date then, we have large databases of genetic variants that were found in one study or another to correlate to various mental traits, like depression, IQ, ADHD, risk-taking behavior, etc. It doesn’t stop there, though. There are studies purporting to show genetic correlations for things as varied as church attendance, being a gym rat, loneliness, ice cream flavor preference, political affiliation, and potentially anything else that you can formulate into a simple questionnaire. Yet, in none of these cases, have we been able to identify what any of these genes would actually do to cause someone to be depressed, prefer chocolate ice cream over vanilla, or vote for Brexit. There is a kind of absurdity to the very notion. In truth, I would argue that this science isn’t a whole lot more definitive than phrenology was a century or two earlier (phrenology was the supposed scientific study of measuring the bumps on a person’s skull to predict mental traits).

Perhaps, at this point, you are wondering why I care about this? There are a few reasons. First, is the question of eugenics, which is the idea that some individuals carry “inferior” (or superior) genes. This idea led to the institutionalization and sterilization of many people in the US and elsewhere in the first half of the 20th century, and culminated in the various Nazi atrocities. Because of its sordid history, few people would actually refer to themselves as eugenicists anymore, but discarding the label doesn’t make these ideas go away and books like Charles Murray’s “The Bell Curve” which suggests racial disparities in IQ, is a good example of how this kind of thinking persists. In fact, James Watson, one of the scientists credited with discovering the DNA double helix, openly suggests that people of African descent are genetically less intelligent than people of European descent. Genetic studies are often used as a kind of justification for these ideas. You will find some of them touted on neo-Nazi websites, for example.

There are less obvious issues related to this way of looking at the world through a genetic lens, however. If, for example, you take it as a fact that ADHD is a genetic disorder, then you are effectively making it a physical disease, which is going to change your approach to its treatment, generally involving giving children amphetamines and similar drugs, without really assessing whether our society and culture have created conditions and expectations that, when not met, are viewed as an individual disease. In itself, this is a cultural malady. If we assume that things like depression, alcohol and drug addiction, criminal behavior, etc., are all “in our genes,” then we can focus our attention on the “diseased” individuals, figuring out what is wrong with them, and why they can’t just be “normal,” and focus our treatment or approach accordingly. This mindset pervades many aspects of our society and has the potential for negative consequences for the individual and society as a whole.

Lastly, I take issue with what I think is a conscious intent behind endlessly conducting these genetic studies in order to foster a framework in which genes are presumed to be driving our behavior, as if this explanation is a human need. I suppose many people find a kind of comfort in the idea, because it provides a sense of certainty about who and what we are. This drive for certainty is, I think, one of the defining aspects of our society. It precedes our political, social and intellectual opinions. I find it to be a stifling and possibly harmful way to view the human condition. The studies are not showing what they purport to be showing. You may still want to believe that we are genetically programmed, and that science will bear all this out at some later date but, in the meantime, I want to sow a bit of healthy uncertainty.