genetics

Genetic data sets skew too European, threatening to narrow who will benefit from future advances.

Louis Reed on Unsplash

Genomics has begun its golden age. Just 20 years ago, sequencing a single genome cost nearly $3 billion and took over a decade. Today, the same feat can be achieved for a few hundred dollars and the better part of a day . Suddenly, the prospect of sequencing not just individuals, but whole populations, has become feasible.

The genetic differences between humans may seem meager, only around 0.1 percent of the genome on average, but this variation can have profound effects on an individual's risk of disease, responsiveness to medication, and even the dosage level that would work best.

Already, initiatives like the U.K.'s 100,000 Genomes Project - now expanding to 1 million genomes - and other similarly massive sequencing projects in Iceland and the U.S., have begun collecting population-scale data in order to capture and study this variation.

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Farhan Mitha
Farhan Mitha is a freelance science writer based in London. He regularly writes about biotechnology, synthetic biology, and natural history, and is currently studying for a master's degree in Evolutionary Genomics. Find him on Twitter @FarhanMitha.

A woman does a DNA test with a cotton swab at home.

(© Nataliya/Adobe)


Leading direct-to-consumer (DTC) genetic testing companies are continuously unveiling novel ways to leverage their vast stores of genetic data.

"23andMe will tell you what diseases you have and then sell you the drugs to treat them."

As reported last week, 23andMe's latest concept is to develop and license new drugs using the data of consumers who have opted in to let their information be used for research. To date, over 10 million people have used the service and around 80 percent have opted in, making its database one of the largest in the world.

Culture researcher Dr. Julia Creet is one of the foremost experts on the DTC genetic testing industry, and in her forthcoming book, The Genealogical Sublime, she bluntly examines whether such companies' motives and interests are in sync with those of consumers.

Leapsmag caught up with Creet about the latest news and the wider industry's implications for health and privacy.

23andMe has just announced that it plans to license a newly developed anti-inflammatory drug, the first one created using its customers' genetic data, to Almirall, a pharma company in Spain. What's your take?

I think this development is the next step in the evolution of the company and its "double-sided" marketing model. In the past, as it enticed customers to give it their DNA, it sold the results and the medical information divulged by customers to other drug companies. Now it is positioning itself to reap the profits of a new model by developing treatments itself.

Given that there are many anti-inflammatory drugs on the market already, whatever Almirall produces might not have much of an impact. We might see this canny move as a "proof of concept," that 23andMe has learned how to "leverage" its genetic data without having to sell them to a third party. In a way, the privacy provisions will be much less complicated, and the company stands to attract investment as it turns itself into [a pseudo pharmaceutical company], a "pharma-psuedocal" company.

Emily Drabant Conley, the president of business development, has said that 23andMe is pursuing other drug compounds and may conduct their own clinical trials rather than licensing them out to their existing research partners. The end goal, it seems, is to make direct-to-consumer DNA testing to drug production and sales back to that same consumer base a seamless and lucrative circle. You have to admit it's a brilliant business model. 23andMe will tell you what diseases you have and then sell you the drugs to treat them.

In your new book, you describe how DTC genetic testing companies have capitalized on our innate human desire to connect with or ancestors and each other. I quote you: "This industry has taken that potent, spiritual, all-too-human need to belong... and monetized it in a particularly exploitative way." But others argue that DTC genetic testing companies are merely providing a service in exchange for fair-market compensation. So where does exploitation come into the picture?

Yes, the industry provides a fee for service, but that's only part of the story. The rest of the story reveals a pernicious industry that hides its business model behind the larger science project of health and heredity. All of the major testing companies play on the idea of "lack," that we can't know who we are unless we buy information about ourselves. When you really think about it, "Who do you think you are?" is a pernicious question that suggests that we don't or can't know who we or to whom we are related without advanced data searches and testing. This existential question used to be a philosophical question; now the answers are provided by databases that acquire more valuable information than they provide in the exchange.

"It's a brilliant business model that exploits consumer naiveté."

As you've said before, consumers are actually paying to be the product because the companies are likely to profit more from selling their genetic data. Could you elaborate?

The largest databases, AncestryDNA and 23andMe, have signed lucrative agreements with biotech companies that pay them for the de-identified data of their customers. What's so valuable is the DNA combined with the family relationships. Consumers provide the family relationships and the companies link and extrapolate the results to larger and larger family trees. Combined with the genetic markers for certain diseases, or increased susceptibility to certain diseases, these databases are very valuable for biotech research.

None of that value will ever be returned to consumers except in the form of for-profit drugs. Ancestry, in particular, has removed all information about its "research partners" from its website, making it very difficult to see how it is profiting from its third-party sales. 23andMe is more open about its "two-sided business model," but encourages consumers to donate their information to science. It's a brilliant business model that exploits consumer naiveté.

A WIRED journalist wrote that "23andMe has been sharing insights gleaned from consented customer data with GSK and at least six other pharmaceutical and biotechnology firms for the past three and a half years." Is this a consumer privacy risk?

I don't see that 23andMe did anything to which consumers didn't consent, albeit through arguably unreadable terms and conditions. The part that worries me more is the 300 phenotype data points that the company has collected on its consumers through longitudinal surveys designed, as Anne Wojcicki, CEO and Co-founder of 23andMe, put it, "to circumvent medical records and just self-report."

Everyone is focused on the DNA, but it's the combination of genetic samples, genealogical information and health records that is the most potent dataset, and 23andMe has figured out a way to extract all three from consumers.

Rachele Hendricks-Sturrup
Rachele Hendricks-Sturrup is a Doctor of Health Science, author, and scholar on ethical, legal, and social issues around the use and processing of consumer-generated health and genetics data.
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Studies of twins have played an important role in determining that genetic differences play a role in the development of differences in behavior.

(Photo by Jelleke Vanooteghem on Unsplash)


[Editor's Note: This essay is in response to our current Big Question, which we posed to experts with different perspectives: "How should DNA tests for intelligence be used, if at all, by parents and educators?"]

Imagine a world in which pregnant women could go to the doctor and obtain a simple inexpensive genetic test of their unborn child that would allow them to predict how tall he or she would eventually be. The test might also tell them the child's risk for high blood pressure or heart disease.

Can we use DNA not to understand, but to predict who is going to be intelligent or extraverted or mentally ill?

Even more remarkable -- and more dangerous -- the test might predict how intelligent the child would be, or how far he or she could be expected to go in school. Or heading further out, it might predict whether he or she will be an alcoholic or a teetotaler, or straight or gay, or… you get the idea. Is this really possible? If it is, would it be a good idea? Answering these questions requires some background in a scientific field called behavior genetics.

Differences in human behavior -- intelligence, personality, mental illness, pretty much everything -- are related to genetic differences among people. Scientists have known this for 150 years, ever since Darwin's half-cousin Francis Galton first applied Shakespeare's phrase, "Nature and Nurture" to the scientific investigation of human differences. We knew about the heritability of behavior before Mendel's laws of genetics had been re-discovered at the end of the last century, and long before the structure of DNA was discovered in the 1950s. How could discoveries about genetics be made before a science of genetics even existed?

The answer is that scientists developed clever research designs that allowed them to make inferences about genetics in the absence of biological knowledge about DNA. The best-known is the twin study: identical twins are essentially clones, sharing 100 percent of their DNA, while fraternal twins are essentially siblings, sharing half. To the extent that identical twins are more similar for some trait than fraternal twins, one can infer that heredity is playing a role. Adoption studies are even more straightforward. Is the personality of an adopted child more like the biological parents she has never seen, or the adoptive parents who raised her?

Twin and adoption studies played an important role in establishing beyond any reasonable doubt that genetic differences play a role in the development of differences in behavior, but they told us very little about how the genetics of behavior actually worked. When the human genome was finally sequenced in the early 2000s, and it became easier and cheaper to obtain actual DNA from large samples of people, scientists anticipated that we would soon find the genes for intelligence, mental illness, and all the other behaviors that were known to be "heritable" in a general way.

But to everyone's amazement, the genes weren't there. It turned out that there are thousands of genes related to any given behavior, so many that they can't be counted, and each one of them has such a tiny effect that it can't be tied to meaningful biological processes. The whole scientific enterprise of understanding the genetics of behavior seemed ready to collapse, until it was rescued -- sort of -- by a new method called polygenic scores, PGS for short. Polygenic scores abandon the old task of finding the genes for complex human behavior, replacing it with black-box prediction: can we use DNA not to understand, but to predict who is going to be intelligent or extraverted or mentally ill?

Prediction from observing parents works better, and is far easier and cheaper, than anything we can do with DNA.

PGS are the shiny new toy of human genetics. From a technological standpoint they are truly amazing, and they are useful for some scientific applications that don't involve making decisions about individual people. We can obtain DNA from thousands of people, estimate the tiny relationships between individual bits of DNA and any outcome we want — height or weight or cardiac disease or IQ — and then add all those tiny effects together into a single bell-shaped score that can predict the outcome of interest. In theory, we could do this from the moment of conception.

Polygenic scores for height already work pretty well. Physicians are debating whether the PGS for heart disease are robust enough to be used in the clinic. For some behavioral traits-- the most data exist for educational attainment -- they work well enough to be scientifically interesting, if not practically useful. For traits like personality or sexual orientation, the prediction is statistically significant but nowhere close to practically meaningful. No one knows how much better any of these predictions are likely to get.

Without a doubt, PGS are an amazing feat of genomic technology, but the task they accomplish is something scientists have been able to do for a long time, and in fact it is something that our grandparents could have done pretty well. PGS are basically a new way to predict a trait in an individual by using the same trait in the individual's parents — a way of observing that the acorn doesn't fall far from the tree.

The children of tall people tend to be tall. Children of excellent athletes are athletic; children of smart people are smart; children of people with heart disease are at risk, themselves. Not every time, of course, but that is how imperfect prediction works: children of tall parents vary in their height like anyone else, but on average they are taller than the rest of us. Prediction from observing parents works better, and is far easier and cheaper, than anything we can do with DNA.

But wait a minute. Prediction from parents isn't strictly genetic. Smart parents not only pass on their genes to their kids, but they also raise them. Smart families are privileged in thousands of ways — they make more money and can send their kids to better schools. The same is true for PGS.

The ability of a genetic score to predict educational attainment depends not only on examining the relationship between certain genes and how far people go in school, but also on every personal and social characteristic that helps or hinders education: wealth, status, discrimination, you name it. The bottom line is that for any kind of prediction of human behavior, separation of genetic from environmental prediction is very difficult; ultimately it isn't possible.

Still, experts are already discussing how to use PGS to make predictions for children, and even for embryos.

This is a reminder that we really have no idea why either parents or PGS predict as well or as poorly as they do. It is easy to imagine that a PGS for educational attainment works because it is summarizing genes that code for efficient neurological development, bigger brains, and swifter problem solving, but we really don't know that. PGS could work because they are associated with being rich, or being motivated, or having light skin. It's the same for predicting from parents. We just don't know.

Still, experts are already discussing how to use PGS to make predictions for children, and even for embryos.

For example, maybe couples could fertilize multiple embryos in vitro, test their DNA, and select the one with the "best" PGS on some trait. This would be a bad idea for a lot of reasons. Such scores aren't effective enough to be very useful to parents, and to the extent they are effective, it is very difficult to know what other traits might be selected for when parents try to prioritize intelligence or attractiveness. People will no doubt try it anyway, and as a matter of reproductive freedom I can't think of any way to stop them. Fortunately, the practice probably won't have any great impact one way or another.

That brings us to the ethics of PGS, particularly in the schools. Imagine that when a child enrolls in a public school, an IQ test is given to her biological parents. Children with low-IQ parents are statistically more likely to have low IQs themselves, so they could be assigned to less demanding classrooms or vocational programs. Hopefully we agree that this would be unethical, but let's think through why.

First of all, it would be unethical because we don't know why the parents have low IQs, or why their IQs predict their children's. The parents could be from a marginalized ethnic group, recognizable by their skin color and passed on genetically to their children, so discriminating based on a parent's IQ would just be a proxy for discriminating based on skin color. Such a system would be no more than a social scientific gloss on an old-fashioned program for perpetuating economic and cognitive privilege via the educational system.

People deserve to be judged on the basis of their own behavior, not a genetic test.

Assigning children to classrooms based on genetic testing would be no different, although it would have the slight ethical advantage of being less effective. The PGS for educational attainment could reflect brain-efficiency, but it could also depend on skin color, or economic advantage, or personality, or literally anything that is related in any way to economic success. Privileging kids with higher genetic scores would be no different than privileging children with smart parents. If schools really believe that a psychological trait like IQ is important for school placement, the sensible thing is to administer the children an actual IQ test – not a genetic test.

IQ testing has its own issues, of course, but at least it involves making decisions about individuals based on their own observable characteristics, rather than on characteristics of their parents or their genome. If decisions must be made, if resources must be apportioned, people deserve to be judged on the basis of their own behavior, the content of their character. Since it can't be denied that people differ in all sorts of relevant ways, this is what it means for all people to be created equal.

[Editor's Note: Read another perspective in the series here.]

Eric Turkheimer
Eric Turkheimer is a professor of psychology at the University of Virginia. From 2003 to 2008 he was Director of Clinical Training. Turkheimer has been an Associate Editor for Psychological Assessment, is currently an Associate Editor of Behavior Genetics and has served on the editorial boards of Journal of Personality and Social Psychology and Perspectives on Psychological Science. In 2009, he was awarded the James Shields Memorial Award for outstanding research in Behavioral Genetics. He is a past President of the Behavior Genetics Association. His current research includes detection of G by E interactions in twin studies of intelligence, development of statistical methods for analyses of children of twins, and the use of twins to establish quasi-experimental control in studies of developmental associations between parenting behavior and offspring outcomes in adolescence. His overarching research goal is to explore the possibilities and limitations of behavior genetics as a means of expanding the scope and rigor of human behavioral science.

A child prodigy considers a math equation.

(© tournee/Adobe)


[Editor's Note: This essay is in response to our current Big Question, which we posed to experts with different perspectives: "How should DNA tests for intelligence be used, if at all, by parents and educators?"]

It's 2019. Prenatal genetic tests are being used to help parents select from healthy and diseased eggs. Genetic risk profiles are being created for a range of common diseases. And embryonic gene editing has moved into the clinic. The science community is nearly unanimous on the question of whether we should be consulting our genomes as early as possible to create healthy offspring. If you can predict it, let's prevent it, and the sooner, the better.

There are big issues with IQ genetics that should be considered before parents and educators adopt DNA IQ predictions.

When it comes to care of our babies, kids, and future generations, we are doing things today that we never even dreamed would be possible. But one area that remains murky is the long fraught question of IQ, and whether to use DNA science to tell us something about it. There are big issues with IQ genetics that should be considered before parents and educators adopt DNA IQ predictions.

IQ tests have been around for over a century. They've been used by doctors, teachers, government officials, and a whole host of institutions as a proxy for intelligence, especially in youth. At times in history, test results have been used to determine whether to allow a person to procreate, remain a part of society, or merely stay alive. These abuses seem to be a distant part of our past, and IQ tests have since garnered their fair share of controversy for exhibiting racial and cultural biases. But they continue to be used across society. Indeed, much of the literature aimed at expecting parents justifies its recommendations (more omegas, less formula, etc.) based on promises of raising a baby's IQ.

This is the power of IQ testing sans DNA science. Until recently, the two were separate entities, with IQ tests indicating a coefficient created from individual responses to written questions and genetic tests indicating some disease susceptibility based on a sequence of one's DNA. Yet in recent years, scientists have begun to unlock the secrets of inherited aspects of intelligence with genetic analyses that scan millions of points of variation in DNA. Both bench scientists and direct-to-consumer companies have used these new technologies to find variants associated with exceptional IQ scores. There are a number of tests on the open market that parents and educators can use at will. These tests purport to reveal whether a child is inherently predisposed to be intelligent, and some suggest ways to track them for success.

I started looking into these tests when I was doing research for my book, "Social by Nature: The Promise and Peril of Sociogenomics." This book investigated the new genetic science of social phenomena, like educational attainment and political persuasion, investment strategies, and health habits. I learned that, while many of the scientists doing much of the basic research into these things cautioned that the effects of genetic factors were quite small, most saw testing as one data point among many that could help to somehow level the playing field for young people. The rationale went that in certain circumstances, some needed help more than others. Why not put our collective resources together to help them?

Good nutrition, support at home, and access to healthcare and education make a huge difference in how people do.

Some experts believed so strongly in the power of DNA behavioral prediction that they argued it would be unfair not to use predictors to determine a kid's future, prevent negative outcomes, and promote the possibility for positive ones. The educators out in the wider world that I spoke with agreed. With careful attention, they thought sociogenomic tests could help young people get the push they needed when they possessed DNA sequences that weren't working in their favor. Officials working with troubled youth told me they hoped DNA data could be marshaled early enough that kids would thrive at home and in school, thereby avoiding ending up in their care. While my conversations with folks centered around sociogenomic data in general, genetic IQ prediction was completely entangled in it all.

I present these prevailing views to demonstrate both the widespread appeal of genetic predictors as well as the well-meaning intentions of those in favor of using them. It's a truly progressive notion to help those who need help the most. But we must question whether genetic predictors are data points worth looking at.

When we examine the way DNA IQ predictors are generated, we see scientists grouping people with similar IQ test results and academic achievements, and then searching for the DNA those people have in common. But there's a lot more to scores and achievements than meets the eye. Good nutrition, support at home, and access to healthcare and education make a huge difference in how people do. Therefore, the first problem with using DNA IQ predictors is that the data points themselves may be compromised by numerous inaccuracies.

We must then ask ourselves where the deep, enduring inequities in our society are really coming from. A deluge of research has shown that poor life outcomes are a product of social inequalities, like toxic living conditions, underfunded schools, and unhealthy jobs. A wealth of research has also shown that race, gender, sexuality, and class heavily influence life outcomes in numerous ways. Parents and caregivers feed, talk, and play differently with babies of different genders. Teachers treat girls and boys, as well as members of different racial and ethnic backgrounds, differently to the point where they do better and worse in different subject areas.

Healthcare providers consistently racially profile, using diagnostics and prescribing therapies differently for the same health conditions. Access to good schools and healthcare are strongly mitigated by one's race and socioeconomic status. But even youth from privileged backgrounds suffer worse health and life outcomes when they identify or are identified as queer. These are but a few examples of the ways in which social inequities affect our chances in life. Therefore, the second problem with using DNA IQ predictors is that it obscures these very real, and frankly lethal, determinants. Instead of attending to the social environment, parents and educators take inborn genetics as the reason for a child's successes or failures.

It is time that we shift our priorities from seeking genetic causes to fixing the social causes we know to be real.

The other problem with using DNA IQ predictors is that research into the weightiness of DNA evidence has shown time and again that people take DNA evidence more seriously than they do other kinds of evidence. So it's not realistic to say that we can just consider IQ genetics as merely one tiny data point. People will always give more weight to DNA evidence than it deserves. And given its proven negligible effect, it would be irresponsible to do so.

It is time that we shift our priorities from seeking genetic causes to fixing the social causes we know to be real. Parents and educators need to be wary of solutions aimed at them and their individual children.

[Editor's Note: Read another perspective in the series here.]

Catherine Bliss
Catherine Bliss is Associate Professor of Sociology at UCSF. She is the author of Race Decoded: The Genomic Fight for Social Justice and Social by Nature: The Promise and Peril of Sociogenomics.

A woman gives a DNA sample at a Pheramor-sponsored event.

(Pheramor)


Brittany Barreto first got the idea to make a DNA-based dating platform nearly 10 years ago when she was in a college seminar on genetics. She joked that it would be called GeneHarmony.com.

Pheramor and startups, like DNA Romance and Instant Chemistry, both based in Canada, claim to match you to a romantic partner based on your genetics.

The idea stuck with her while she was getting her PhD in genetics at Baylor College of Medicine, and in March 2018, she launched Pheramor, a dating app that measures compatibility based on physical chemistry and what the company calls "social alignment."

"I wanted to use genetics and science to help people connect more. Our world is so hungry for connection," says Barreto, who serves as Pheramor's CEO.

With the direct-to-consumer genetic testing market booming, more and more companies are looking to capitalize on the promise of DNA-based services. Pheramor and startups, like DNA Romance and Instant Chemistry, both based in Canada, claim to match you to a romantic partner based on your genetics. It's an intriguing alternative to swiping left or right in hopes of finding someone you're not only physically attracted to but actually want to date. Experts say the science behind such apps isn't settled though.

For $40, Pheramor sends you a DNA kit to swab the inside of your cheek. After you mail in your sample, Pheramor analyzes your saliva for 11 different HLA genes, a fraction of the more than 200 genes that are thought to make up the human HLA complex. These genes make proteins that regulate the immune system by helping protect against invading pathogens.

It takes three to four weeks to get the results backs. In the meantime, users can still download the app and start using it before their DNA results are ready. The app asks users to link their social media accounts, which are fed into an algorithm that calculates a "social alignment." The algorithm takes into account the hashtags you use, your likes, check-ins, posts, and accounts you follow on Facebook, Twitter, and Instagram.

The DNA test results and social alignment algorithm are used to calculate a compatibility percentage between zero and 100. Barreto said she couldn't comment on how much of that score is influenced by the algorithm and how much comes from what the company calls genetic attraction. "DNA is not destiny," she says. "It's not like you're going to swab and I'll send you your soulmate."

Despite its name, Pheramor doesn't actually measure pheromones, chemicals released by animals that affect the behavior of others of the same species. That's because human pheromones have yet to be identified, though they've been discovered throughout the animal kingdom in moths, mice, rabbits, pigs, and many other insects and mammals. The HLA genes Pheramor analyzes instead are the human version of the major histocompatibility complex (MHC), a gene group found in many species.

The connection between HLA type and attraction goes back to the 1970s, when researchers found that inbred male mice preferred to mate with female mice with a different MHC rather than inbred female mice with similar immune system genes. The researchers concluded that this mating preference was linked to smell. The idea is that choosing a mate with different MHC genes gives animals an evolutionary advantage in terms of immune system defense.

The couples who had more dissimilar HLA types reported a more satisfied sex life and satisfied partnership, but it was a small effect.

In the 1990s, Swiss scientists wanted to see if body odor also had an effect on human attraction. In a famous experiment known as the "sweaty T-shirt study", they recruited 49 women to sniff sweaty, unwashed T-shirts from 44 men and put each in a box with a smelling hole and describe the odors of every shirt. The study found that women preferred the scents of T-shirts worn by men who were immunologically different from them compared to men whose HLA genes were similar to their own.

"The idea is, if you are very similar with your partner in HLA type then your offspring is similar in terms of HLA. This reduces your resistance against pathogens," says Illona Croy, a psychologist at the Technical University of Dresden who has studied HLA type in relation to sexual attraction in humans.

In a 2016 study Pheramor cites on its website, Croy and her colleagues tested the HLA types of 250 couples—all of them university students—and asked them how satisfied they were with their partnerships, with their sex lives, and with the odors of their partners. The couples who had more dissimilar HLA types reported a more satisfied sex life and satisfied partnership, but Croy cautions that it was a small effect. "It's not like they were super satisfied or not satisfied at all. It's a slight difference," she says.

Croy says we're much more likely to choose a partner based on appearance, sense of humor, intelligence and common interests.

Other studies have reported no preference for HLA difference in sexual attraction. Tristram Wyatt, a zoologist at the University of Oxford in the U.K. who studies animal pheromones, says it's been difficult to replicate the original T-shirt study. And one of the caveats of the original study is that women who were taking birth control pills preferred men who were more immunologically similar.

"Certainly, we learn to really like the smell of our partners," Wyatt says. "Whether it's the reason for choosing them in the first place, we really don't know."

Wyatt says he's skeptical of DNA-based dating apps because there are many subtypes of HLA genes, meaning there's a fairly low chance that your HLA type and your romantic partner's would be an exact match, anyway. It's why finding a suitable match for a bone marrow transplant is difficult; a donor's HLA type has to be the same as the recipient's.

"What it means is that since we're all different, it's hard statistically to say who the best match will be," he says.

DNA-based dating apps haven't yet gone mainstream, but some people seem willing to give them a try. Since Pheramor's launch a little over a year ago, about 10,000 people have signed up to use the app, about half of which have taken the DNA test, Barreto says. By comparison, an estimated 50 million people use Tinder, which has been around since 2012, and about 40 million people are on Bumble, which was released in 2014.

In April, Barreto launched a second service, this one for couples, called WeHaveChemistry.com. A $139 kit includes two genetic tests, one for you and your partner, and a detailed DNA report on your sexual compatibility.

Unlike the Phermor app, WeHaveChemistry doesn't provide users with a numeric combability score but instead makes personalized recommendations based on your genetic results. For instance, if the DNA test shows that your HLA genes are similar, Barreto says, "We might recommend pheromone colognes, working out together, or not showering before bed to get your juices running."

Despite her own research on HLA and sexual compatibility, Croy isn't sure how knowing HLA type will help couples. However, some researchers are doing studies on whether HLA types are related to certain cases of infertility, and this is where a genetic test might be very useful, says Croy.

"Otherwise, I think it doesn't matter whether we're HLA compatible or not," she says. "It might give you one possible explanation about why your sexual life isn't as satisfactory as it could be, but there are many other factors that play a role."

Emily Mullin
Emily Mullin is the acting editor of Leaps.org. Most recently, she was a staff writer covering biotechnology at OneZero, Medium's tech and science publication. Before that, she was the associate editor for biomedicine at MIT Technology Review. Her stories have also appeared in The Washington Post, New York Times, Wall Street Journal, Scientific American, National Geographic and Smithsonian Magazine.