Race: What’s genes got to do with it?

By Shweta Ramdas

The Human Genome Project released the sequence of the human genome in 2001. On its heels came the question: what does genetics tell us about race?

The length of our genome (the DNA sequence contained within our cells) is 3 billion letters. As you have probably heard, any two humans are on average 99.9% identical. The DNA of the person standing next to me is likely to differ from my DNA at 1 in 1000 letters. However, thanks to centuries of isolated mating within an ethnicity (and a lack of mating across ethnicities, usually due to geography) my genome is more likely to look like the genome of another Indian than like the genome of someone from Africa or China. In fact, if you take my DNA sequence and try to figure out which part of the world I’m from, you can do so with increasing accuracy. I participated in a genetic study at the University of Michigan, and voilà, it is now confirmed that I am South Asian.

The two axes of the figure represent the maximum information contained in my genetic data. Plotting genetic data on these axes can reveal important groupings of the samples. In this plot, each point represents genetic data from a publicly available sample of known ancestry, each ancestry in a different color. Comparing my data to these samples of known ancestry allows us to determine mine. My sample lies in the South Asian cloud of data.

Is there a connection between race and genetics? Clearly, my genetics do correctly identify my ancestry. Leaders of the Human Genome Project have been quick to respond to the question. ‘Race’ or ‘ancestry’ is a concept that has been defined culturally and socially, not biologically. Is there a connection between race and genetics? Yes. But although there is a relation between genetics and race, there is no genetic basis for race. Racial differences in genetics simply reflects social constructs; it is not the other way around. There simply is no ‘race’ gene in our genome: genetically, race is defined by us being more similar in our genetic makeup to our neighbors.

There is also no known genetic basis for more societal differences we see across populations; differences in behavioral attributes (for instance confidence, independence) can have their roots in social and economic factors and history. Every once in a while, we spot arguments from various outlets that seek to explain population differences in one trait or another through genetics; the latest is this book by Nicholas Wade which claims that different regions of the world have different political systems because societies have genetic predispositions towards certain styles of leadership. A democracy gene? Not quite. This controversial book has been met with resistance from geneticists. While it is tempting to look for genetic arguments to explain differences between cultures, there is little evidence to support such hypotheses for complex behaviors. Arguments such as those by Wade are dangerous because genetic explanations allow us to set population differences in stone. It is only too convenient to ascribe differences in social or behavioral traits to genetics, but the evidence so far does not support this. For instance, there are differences in IQ between people of different races. Does this mean a people are genetically less intelligent than other groups? No. Such differences can also be explained by cultural factors (for example, some cultural groups are better ‘trained’ for IQ tests and thus give higher scores). But you could ask: Could there be a genetic reason for this difference? Hypothetically yes, but there is no such evidence. And we have to be wary of using genetic hypothesis to support our pre-existing biases, as phrenology in the 19th and early 20th centuries was used to support the perceived inferiority of Africans.

So while using genetics to explain population differences in behavioral traits has no standing, there is at least one area where genetic differences between races is, and should be, taken into account: drug responses. ‘Pharmacogenetics’ is the study of how genetic differences can affect your response to various drugs. For instance, a protein called CYP2C9 is responsible for the metabolism of several drugs, including the anti-clotting drug warfarin. However, certain versions of the CYP2C9 protein break down warfarin more slowly. This leads to a greater amount of warfarin in these patients’ bodies, which could be poisonous. Where does race come in? People of European ancestry are more likely to have the ‘slow metabolizing’ variant of this protein, whereas African Americans are more likely to have the fast metabolizing variant. This means that a lower dosage of warfarin customized for a European patient group due to their slow metabolism is unlikely to be effective in populations with a different genetic distribution. These differences have to be taken into account for the most optimal treatments (though such approaches come with their fair share of controversy too). The caveat, of course, is that race is NOT a good substitute for individual genetics as self-identified racial identifications are socially constructed and not an indicator for genetics. Unfortunately, race may simply be the best we have until genome sequencing becomes more common.

The president of the American Society for Human Genetics, Neil Risch, started off the 2015 annual meeting with this powerful message: “Genetic arguments have no place in the fight for equality and social justice.” The advent of cheap DNA sequencing technology is allowing us to untangle the (often delicate and politically flammable) relations between genetics and race. For genetics to support our inherent biases certainly has no room in research. But until every person is treated as a unique individual with his/her genome sequenced (and until we can use that information to its full advantage), we should consider the information that race provides about a person’s health. Recognizing and using the relationship between genetics and race to improve health care, while being careful to stay away from false implications and biases involved, is an important tool in achieving social equality.

About the author

Shweta is a graduate student in Bioinformatics at the University of Michigan. Her research involves studying computational methods to understand the genetic basic of psychiatric disease. Her undergraduate degree is from the National University of Singapore where she studied computational biology. Outside of research, Shweta enjoys reading, yoga, and figuring out the genetic basis for being a muggle. Follow Shweta on Twitter.

Read all posts by Shweta here.