A couple of weeks ago I received an email from a company called GBHealthwatch with the subject header “Eat Right for Your Genes”…Funny, I didn’t even know my genes were hungry.
No, really--genes can’t be hungry, nor can they be read like blueprints, tell us our future, or effectively predict what our bodies or behavior look like (at least not by themselves). This is yet another in the recent landslide of ads, news stories and websites that seem unable to understand basic biology: genes are not fortune tellers.
Simply identifying which version of a given gene you might have tells you extremely little about any complex aspect of being you. Sure, in a teeny minority of cases there are some clear connections between specific genetic sequences (alleles or forms of a gene) and bodily outcomes—but these are usually horrific lethal diseases (like Tay-Sachs) and not things like behavior, temperament, health, or even height, nose shape, etc…
Ok, there are some patterns and relationships between certain genetic sequences and certain health outcomes, but they are almost never simple or clear cut. For example, variable sequences the gene APOE found on chromosome 19 have been identified as associated with patterns of atherosclerosis, a rare condition called hyperlipoproteinemia type III, age-related macular degeneration, and the onset of Alzheimer’s. The APOE gene contains the code for a protein that impacts the movement and distribution of cholesterol and other lipids in the body. This is one of the genes that GBHealthworks tells us to eat right for.
But this is not simple—different forms of the gene are associated with different possible disease outcomes and there is no one-to-one connection, just lots of complex associations between the gene’s products interacting with other gene’s product and the possibility of certain diseases. For example, recent work by a research team based at UCLA in conjunction with NIH (alongside of many other project) shows there are connections between this gene’s products and the regulation of cholesterol and other lipids (fats) at many places in the body and that some versions of the gene seem to do this better than others. They find that in one form of the gene, its product interacts with many other molecules and enzymes in the brain in a way that might be less effective at clearing cholesterol. In some cases this might translate to higher late onset Alzheimer’s risk.
In other words, the gene and its products are part of a system—by itself it might indicate some correlations or possibilities, but it will not, and cannot, predict specific outcomes. One needs to know about the whole picture in which the gene exists to get an idea of what it might be able to predict about us. That picture includes: which copies of the gene the person has, what the sequences of DNA near the gene are, what patterns of epigenetic markers might have been laid down on that individual’s genome near the gene (or in places that turn that section of DNA on and off), what the genes products look like in the individual in question, and what the other allied gene products it works with look like. We also need to know the life history of the individual we are looking at, including their health and environmental histories, and of course, what have their social and psychological lives been like.
This is a mess—and this is for a gene for which we have a really good idea how its products work. Just knowing which copy of the gene we have is like having one piece of a 10,000 piece picture puzzle and trying to predict what the picture will look like.
So how do we “eat” right for our genes? Well, GBHealthworks tells us that we should use low-fat, high-carb diets for APOE4 carriers while high-fat, low-carb diets are recommended for APOE2 carriers…Really? They are going to make serious and impactful dietary recommendations based on a single gene? What about all the other factors?
But wait, it gets worse.
GBHealthworks also tells us that “The DRD2 and OPRM1 genes function in the brain reward system. Variations in these genes are associated with emotional eating and weight gain. About 11% Caucasians and 14% Asians carry a combination of these two genes that increase their risk for binge eating disorder.” Ok, I am not going to even rehash the absurdity of the race categories in these kind of medical studies (see here, here, and here) but I will point out that here we have the assertion that a gene combination can give us a higher likelihood of a very complex and psychologically contextual behavioral pattern (emotional eating)—this is not only dubious, it is also duplicitous.
In fact, after freaking you out about your possible genetic condemnation, GBHealthworks goes on to tell you that: “GB HealthWatch scientists have worked out detailed techniques for trigger food control and for smart food choices that can help you cope with cravings. Log in now to see our tips”. Ahh, so the answers are there—you just need to know what version of the genes you have and a healthy lifestyle can be developed.—spoiler alert—we already know a lot about how to live healthy lifestyles even without a genetic screening…there is no evidence that knowing your DNA sequences at particular places is going to improve that (regardless of what you pay!).
What does all of this have to do with psychology and busting myths about human nature?Basically, we all want to believe the myth of DNA: that it provides an explanation for why we are the way we are. However, it is just not true--genes are never more than just a part of the story (albeit an important part)—and they will not provide us with an easy answer to why we look, act and feel the way we do. Next time you get an email that tells you your genes are going to make something happen (good or bad), delete it and go read a book, some good science articles about genetics, or heck—just eat well and go get some exercise.