The Age of DNA-Based Dating Is Here
A woman gives a DNA sample at a Pheramor-sponsored event.
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."
Will religious people reject organ transplants from pigs?
Scientists are getting better at transplanting pig organs into humans. But religious followers of prohibitions on consuming pork may reject these organs, even if their bodies could accept them.
The first successful recipient of a human heart transplant lived 18 days. The first artificial heart recipient lived just over 100.
Their brief post-transplant lives paved the way toward vastly greater successes. Former Vice President Dick Cheney relied on an artificial heart for nearly two years before receiving a human heart transplant. It still beats in his chest more than a decade later.
Organ transplantation recently reached its next phase with David Bennett. He survived for two months after becoming the first recipient of a pig’s heart genetically modified to function in a human body in February. Known as a xenotransplant, the procedure could pave the way for greatly expanding the use of transplanted vital organs to extend human lives.
Clinical trials would have to be held in the U.S. before xenotransplants become widespread; Bennett’s surgery was authorized under a special Food and Drug Administration program that addresses patients with life-threatening medical conditions.
German researchers plan to perform eight pig-to-human heart transplants as part of a clinical trial beginning in 2024. According to an email sent to Leaps.org by three scholars working on the German project, these procedures will focus on one of the reasons David Bennett did not survive longer: A porcine infection from his new heart.
The transplant team will conduct more sensitive testing of the donor organs, “which in all likelihood will be able to detect even low levels of virus in the xenograft,” note the scientists, Katharina Ebner, Jochen Ostheimer and Jochen Sautermeister. They are confident that the risk of infection with a porcine virus in the future will be significantly lower.
Moreover, hearts are not the only genetically modified organs that are being xenotransplanted. A team of surgeons at the University of Alabama at Birmingham successfully transplanted genetically modified pig kidneys into a brain-dead human recipient in September. The kidneys functioned normally for more than three days before the experiment ended. The UAB team is now moving forward with clinical trials focusing on transplanting pig kidneys into human patients.
Some experts believe the momentum for xenotransplantation is building, particularly given the recent successes. “I think there is a strong likelihood this will go mainstream,” says Brendan Parent of NYU Langone Health.
Douglas Anderson, a surgeon who is part of that kidney xenotransplant team, observes that, “organ shortages have been the major issue facing transplantation since its inception” and that xenotransplantation is a potential solution to that quandary. “It can’t be understated the number of people waiting for a kidney on dialysis, which has a significant mortality rate,” he says. According to the advocacy group Donate Life America, more than 100,000 people in the U.S. alone are waiting for a donated organ, and 85 percent of them need a kidney.
Other experts believe the momentum for xenotransplantation is building, particularly given the recent successes. “I think there is a strong likelihood this will go mainstream,” says Brendan Parent, director of transplant ethics and policy at NYU Langone Health, a New York City-based hospital system. Like the UAB team, surgeons at NYU Langone have had success coaxing modified pig kidneys to work in deceased humans.
“There is a genuinely good chance that within a generation, (xenotransplantation) might become very common in reasonably wealthy countries,” says Michael Reiss, professor of science education at University College in London. In addition to his academic position, Reiss sits on the Nuffield Council on Bioethics, a nonprofit that is one of Britain’s most prominent watchdogs regarding medical and scientific issues. Reiss is also an Anglican priest and has studied xenotransplantation from both a scientific and religious point of view.
Moreover, genetic modifications could one day lead to organs being specifically optimized for their recipients. That could ensure issues like donor rejection and the calculated risk of artificially suppressing recipient immune systems become concerns of the past.
Major bioethical, religious concerns
Despite the promise of xenotransplantation, numerous bioethical issues swirl around the procedure. They could be magnified if xenotransplantation evolves from one-off experiments to a routine medical procedure.
One of the biggest is the millennia-long prohibitions Islam and Judaism have had regarding the consumption of pork. Will followers of these religions assume such rules extend to those taboo materials being inserted into a human body?
“Initially, one’s instinctual reaction is that, oh, crumbs! – how are Jews and Muslims going to react to that?” Reiss says. But in a world where science and secularism are accepted on an everyday basis, he notes it is not a significant issue. Reiss points out that valves from pig hearts have been used in human patients for decades without any issues. He adds that both Islam and Judaism waive religious dietary restrictions if a human life is at risk.
“While nobody's saying an individual patient is to be forced to have these, the very high proportion of people who identify as Jews or Muslims when given this option are content with it,” he says.
Concurring with Reiss is Michael Gusamano, professor of health policy at Lehigh University and director of its Center for Ethics. He is currently performing research on the ethics of xenotransplantation for the National Institutes of Health.
“Leaders from all major religions have commented on this and have indicated that this is not inconsistent with religious doctrine,” Gusamano says in written remarks to Leaps.org. “Having said that, it is plausible to believe that some people will assume that this is inconsistent with the teaching of their religion and may object to…receiving a xenotransplant as part of routine medical care.”
A history of clashes
Despite those assurances, science has long clashed with theology. Although Galileo proved the planets revolved around the sun, the Catholic Church found him guilty of heresy and rewarded his discovery with house arrest for the last decade of his life. A revolt occurred in mid-19th century India after native-born soldiers believed the ammunition supplied by their British occupiers had been lubricated with pork and beef tallow. Given they had to use their mouths to tear open ammunition pouches, this violated both the tenets of Islam and Hinduism. And one of the conspiracy theories hatched as a result of COVID-19 was that the vaccines developed to fight the disease were the “mark of the beast” – a sign of impending Armageddon under evangelical Christian theology.
The German xenotransplant research team has encountered such potential concerns when the procedure is regarded through a religious lens. “The pastors in our research suspected that many recipients might feel disgust and revulsion,” they write. “Even beyond these special religious reservations, cultural scripts about pigs as inferior living beings are also generally widespread and effective in the western world, so that here too possible disgust reactions cannot be ruled out.”
The German researchers add that “Jewish and Muslim hospital pastoral workers believe possible considerable problems in this respect, which must be dealt with psychosocially, religiously, and pastorally prior to a possible transplantation in order to strengthen the acceptance of the received organ by the patients and their relatives.”
Parent, the director at NYU Langone, shares a concern that xenotransplantation could move “too fast,” although much of his worry is focused on zoonotic disease transmission – pig viruses jumping into humans as a result of such procedures.
Another ethical issue
Moreover, the way pigs and other animals are raised for transplants could pose future ethical dilemmas.
Reiss notes that pigs raised for medical procedures have to be grown and kept in what are known as a designated pathogen-free facility, or DPF. Such facilities are kept painstakingly antiseptic so as to minimize the risk of zoonotic transmissions. But given pigs are fond of outdoor activities such as wallowing in mud and sleeping on hay, they lead “stunningly boring lives” that they probably do not enjoy, Reiss observes.
Ethical concerns with using pigs may push transplantation medicine into its next logical phase: Growing functional organs for transplant in a laboratory setting.
“There’s no doubt that these research pigs have gotten much better veterinary care, et cetera, (compared to farmed pigs). But it’s not a great life,” Reiss says. “And although it hasn’t so far dominated the discussion, I think as the years go by, rather as we’ve seen with the use of apes and now monkeys in medical research, more and more theologians will get uncomfortable about us just assuming we can do this with…pigs.”
The German research team raises the same concerns, but has taken a fairly sanguine view on the topic. “The impairments of the species-typical behavior will certainly provoke criticism and perhaps also public protest. But the number of animals affected is very small in relation to slaughter cattle,” the German researchers note. “Moreover, the conditions there and also in several animal experiments are far worse.”
Observers say that may push transplantation medicine into its next logical phase: Growing functional organs for transplant in a laboratory setting. Anderson, the UAB transplant surgeon, believes such an accomplishment remains decades away.
But other experts believe there is a moral imperative that xenotransplantation remain a temporary solution. “I think we have a duty to go in that direction,” Parent says. “We have to go that way, with the xenotransplantation process (as) a steppingstone and research path that will be useful for bioengineered organs.”
The Friday Five: Scientists treated this girl's disease before she was born
In this week's Friday Five, scientists treated this girl's rare diseases in utero. Plus, how to lift weights in half the time, electric shocks help people regain the ability to walk, meditation is found to work as well as medication, and much more.
The Friday Five covers five stories in research that you may have missed this week. There are plenty of controversies and troubling ethical issues in science – and we get into many of them in our online magazine – but this news roundup focuses on scientific creativity and progress to give you a therapeutic dose of inspiration headed into the weekend.
Here are the promising studies covered in this week's Friday Five:
- Kids treated for diseases before they're born
- How to lift weights in half the time
- Electric shocks help people regain the ability to walk
- Meditation just as good as medication?
- These foods could pump up your motivation