13 Things to Know About DNA Testing Kits

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The search for our identities—where we came from, what we're made of—is a unifying human experience, and our collective fascination with ourselves as individuals has fueled a booming industry around personal DNA testing. More than 12 million people have had their DNA tested by services like 23andMe and AncestryDNA, and that number is expected to grow substantially in the next few years. But can DNA tests really reveal the nuanced information about ancestry and health that many of us seek? Here are 13 things to know about these personal testing kits.

1. PERSONAL DNA TESTING IS SIMPLE—ALL IT TAKES IS A LITTLE SPIT.

Typically, all you have to do is collect some of your saliva or swab the inside of your cheek, then seal the sample in a container and mail it to the lab in a pre-labeled envelope or box. Six to eight weeks later, you can see the results online.

Most personal DNA tests are relatively affordable: Kits from industry leaders like 23andMe, AncestryDNA, Family Tree DNA, MyHeritage DNA, and Living DNA range from $69 to $199. In some cases, the price depends on which genetic reports a customer opts to receive: For 23andMe, for instance, a test that only aims to analyze your ancestry is cheaper than one that also includes health information. Check out this Wiki chart from the International Society of Genetic Genealogy to compare companies' offerings.

2. THE KITS LOOK FOR GENETIC VARIATIONS CALLED SINGLE NUCLEOTIDE POLYMORPHISMS.

After extracting DNA from your cheek swab or saliva sample, DNA testing companies search your DNA for certain genetic variants. The building blocks of DNA are chemical bases called nucleotides, which come in four varieties—A, T, C, and G (adenine, thymine, cytosine, and guanine, respectively). We have 3 billion pairs of these bases, so 6 billion letters in all, strung together in a sequence. Altogether, this genetic information is called your genome.

DNA testing companies determine which of the four letters is present at many locations in your genome. Much of the sequence is shared among humans, so the companies focus on specific letters that vary from person to person, known as single nucleotide polymorphisms (SNPs). Many SNPs have some biological relevance. For example, having one variant of a specific SNP near the gene OCA2, which codes for a protein believed to be involved in producing the dark pigment melanin, makes it much more likely you’ll have blue or green eyes. Other traits and even some diseases are also associated with certain SNPs, some more strongly than others.

3. KIT ACCURACY CAN VARY BASED ON TESTING METHODS.

According to company spokesperson Scott Hadly, 23andMe can identify SNPs with 99.9 percent accuracy, which is in a plausible range for the methods they use. Since many other major companies use similar techniques, their accuracy may be about equivalent—but not all tests meet the same standards. Recently, one test failed to recognize that a purportedly human DNA sample actually came from a golden retriever named Bailey. It did recommend, though, that based on her genetics, Bailey should take up cycling and basketball. The canine’s results came from the lighthearted Superhero DNA Test, which claims to tell customers about their strength, speed, and intelligence. It only tests for four genetic variants, while the pricier kits can include tens of thousands of variants. (It's also worth noting that no matter how many variants a kit tests for, it can't predict complex traits like intelligence, which are influenced by many different genes and environmental factors.)

You should steer clear of companies that offer dubious predictions about your optimal diet, what sports you'll be good at, and other questionable tips. Experts say using DNA tests to extrapolate this information is at best premature and at worst pseudoscience, especially because the recommendations are often based on just a handful of studies on specific groups of people, commonly white men. "The results that have been acquired in one population are not always generalizable to other populations," Jason Rosenbaum, an assistant professor at the University of Pennsylvania's medical school, tells Mental Floss.

4. DNA CAN REVEAL GENETIC CONNECTIONS—BUT INFORMATION ON SOME POPULATIONS IS LIMITED.

Companies use various methods to determine ancestry, but the tests generally involve comparing the customer's DNA to reference DNA meant to represent populations from different geographical regions. Since most people have at least somewhat mixed heritage, ancestry is often represented in percentages: 26 percent Polish, 14 percent Greek, and so on.

These tests aren’t able to guarantee where your ancestors actually lived—they can’t directly compare your data to DNA from people who lived hundreds of years ago, as Adam Rutherford, a British geneticist, pointed out to Gizmodo. And not all groups of people are equally represented in the reference populations, which can impact how precise your results are. People with European backgrounds are overrepresented in the reference data, while there are fewer references relevant to those whose roots lie in the Middle East or Asia, for example. But as research is done on a more diverse range of people, companies are tweaking their analyses to provide more detailed ancestry information to people from all over the world.

5. SOME HINT AT YOUR DNA'S DISTANT HISTORY—INCLUDING NEANDERTHAL HERITAGE.

All humans alive today can trace their mitochondrial lineage back to one woman nicknamed Mitochondrial Eve, who may have lived in Africa about 150,000–200,000 years ago (although this is a source of perennial debate). She wasn't the first modern human woman or the only woman living at the time; other women from her time also have descendants today. They just don’t have an unbroken line of female descendants like Mitochondrial Eve does.

We inherit our mitochondria—the parts of our cells that make energy—from our mothers. Some companies offer a mitochondrial DNA test that allows you to find your maternal haplogroup, which includes people who all share a maternal ancestor thousands or tens of thousands of years ago.

Men can learn about their paternal line through the Y chromosome, which is passed from father to son; certain SNPs on the Y chromosome can be used to determine a person's paternal haplogroup. (Women can find their paternal haplogroup through their biological father or brother.) There’s a "Y-chromosomal Adam," too, although scientists disagree about whether he lived around the same time as Mitochondrial Eve.

A home DNA test might even tell you that you're a little bit Neanderthal, which is especially common in Caucasian and Asian people. Don't worry about Neanderthals' reputation as dull brutes. We now know they were intelligent, used tools, and had their own complex culture.

6. YOU COULD FIND RELATIVES YOU DIDN'T KNOW YOU HAD.

Many DNA testing services allow customers to see whether other users of the same service are biologically related. This can be a boon for anyone assembling a detailed family tree, as well as any adoptees wondering about their biological families. Several people have discovered siblings they never knew they had through these services. In one case, two women—one adopted through an agency and another adopted by a family who found her in the woods as a baby—realized they were long-lost sisters.

Not everyone is pleased to uncover family secrets, though, and you should proceed with caution before you allow a company to match you with new relatives.

7. DNA TESTS CAN REVEAL HEALTH INFORMATION …

While genetic testing might reveal your inability to detect the unique odor of asparagus pee, most people are seeking deeper information, such as whether they have genetic variants associated with diseases like Alzheimer's or breast cancer.

Genetic risk is all about probability. For example, it may be frightening to learn you have an SNP associated with a tenfold increase in risk for a disease—but if that disease only affects 0.01 percent of people, your risk is still just 0.1 percent. Even if you have a SNP strongly associated with a more common illness and show signs of having it, you should see a doctor to get a proper evaluation.

And having a disease-associated SNP isn't a diagnosis. Rare variants are especially likely to lead to false positives: if a variant is only found in one in a million people, it’s more likely that the positive test result is an error than it would be with a more common variant. Some companies report on genetic variants that doctors and scientists haven't deemed medically useful to test for—which is why combing over every SNP is of dubious use. Shoumita Dasgupta, an associate professor in the biomedical genetics program at Boston University, tells Mental Floss that healthcare providers often don't order tests for these SNPs "because professionals have come to the conclusion that the predictive value of these tests is limited."

8. … INCLUDING YOUR RISK OF CERTAIN KINDS OF CANCER.

In March 2018, the FDA granted 23andMe permission to give customers information about certain mutations in the genes BRCA1 and BRCA2 that dramatically increase the risk for breast and ovarian cancer. Some people with a faulty BRCA gene take precautions to prevent or detect cancer early, including undergoing preventive double mastectomies, as Angelina Jolie famously did in 2013.

An important caveat: This test only screens for three SNPs in the BRCA genes that are connected to a dramatic increase in the risk of developing cancer. A positive result merits a consultation with doctor, but a negative result doesn't necessarily mean you're free from the risk of cancer, hereditary or not.

9. SOME DNA TESTING KITS ARE PRESCRIPTION ONLY.

GeneSight is designed to reveal what psychiatric medications will work best for a particular patient. Fertilome aims to show whether a person has genetic markers associated with increased risk of fertility problems, and is intended to help people make reproductive decisions such as whether to freeze eggs or try another round of in vitro fertilization. However, both Fertilome and GeneSight have faced criticism from experts who say there's not enough evidence that the tests are clinically valuable. They're also expensive: Fertilome costs $950, while GeneSight can cost several hundred dollars (though the price can drop to zero with certain insurance plans).

10. MORE DATA ISN'T ALWAYS BETTER.

With the price of DNA analysis falling rapidly, some companies are offering to analyze the order of all the letters of a customer's DNA—what's called sequencing—rather than just looking at SNPs. Sequencing is important in research and medicine: Dasgupta says she now sees some physicians ordering full sequences of multiple genes or even whole exomes (the protein-coding sequences in the genome) for patients.

Exome sequencing is useful to doctors and scientists because it allows them to look for genetic variants beyond the commonly tested SNPs. But every test has a risk of generating false positives, so excessive testing means an increased risk that a person will receive an incorrect diagnosis. Rosenbaum likens it to MRIs. "It's one reason why we don't just give MRIs to everyone, because you're going to turn up things that lead you to believe there's disease where there isn't disease," he explains.

11. YOUR DNA RESULTS COULD CONTRIBUTE TO RESEARCH.

Some home DNA testing companies ask customers to participate in research, answering questions about everything from their sleep habits to their personalities. The goal is to discover previously unknown associations between genetic variants and specific traits. "The way many genetic studies are designed, the more people who are recruited to the study, the more likely the study will be able to identify genetic factors that impact the trait or condition being studied," Dasgupta says.

Personal DNA testing companies potentially have access to the genetic data of millions of users, giving them a huge opportunity to make these connections. Using customer-provided data, 23andMe has already reported some preliminary discoveries on genetic variants linked to detached earlobes, the risk of Parkinson's disease, and more. Studies based on self-reported information always come with caveats, but they’re common in many fields of research and especially useful when collecting objective data isn't practical or possible. Future research spurred by these observations will reveal whether crowdsourced research like 23andMe's has potential to become part of geneticists' repertoire.

12. YOU COULD POTENTIALLY EARN MONEY FROM YOUR DNA.

One company, Genos, charges $499 to sequence a customer's entire exome, and then offers to connect them with genetic researchers. Participating research partners can offer $50 to $250 to Genos users for completing a study intended to find links between their genetic information and any trait or condition the researchers are studying, including dementia, cancer, and infectious disease. Meanwhile, the newly formed company Nebula proposes to sequence customers' genomes, secure them with blockchain technology, and allow customers to control the data—including selling it to biotech and pharmaceutical companies in exchange for Bitcoin-like cryptocurrency. There’s still potential for privacy issues, however, since there’s no guarantee companies that rent or purchase genetic data will keep it secure.

13. YOUR DNA MIGHT ONE DAY HELP TO CATCH A CRIMINAL.

Recently, police investigators in California arrested a man suspected to be the Golden State Killer, thought to be responsible for dozens of rapes and burglaries and at least 12 murders in California from 1976 to 1986. The suspect left DNA behind at the scene of a 1980 murder; after having the DNA analyzed, the investigators created a fake profile on the genealogy website GEDMatch and uploaded the data, hoping it would turn up some of the killer's relatives. It did—and with the help of genealogy experts, the investigators followed the genetic trail to the Sacramento home of 72-year-old Joseph James DeAngelo, who was a cop during the first several years of the deadly crime spree.

The case has raised ethical and privacy concerns for some experts. Genetic data can be stored indefinitely, and it’s possible to use a person's DNA to make inferences about biological relatives who haven’t even taken DNA tests.

Mapping Technology Reveals 'Lost Cities' on National Geographic

Lin uses his iPad to visualize scanning data of a crusaders' fortress at the lagoon in Acre, Israel.
Lin uses his iPad to visualize scanning data of a crusaders' fortress at the lagoon in Acre, Israel.
Blakeway Productions/National Geographic

Imagine what Pompeii looked like before the lava hit, or Mayan pyramids before the jungle took over. In the past decade, scientists have been able to explore human settlements long since abandoned by using a new wave of accessible technology. Instead of needing an expensive plane and crew to fly aerial sensors, for example, explorers can mount them on cheaper drones and pilot them into previously unreachable areas. The resulting data can tell us more about the past, and the future, than ever before.

That’s the premise of Lost Cities with Albert Lin, a new TV series premiering on National Geographic on Sunday, October 20.

Lin, an engineer and National Geographic Explorer, uses cutting-edge tools to shed light on centuries-old cities in the most beautiful places on Earth. Ground-penetrating radar reveals buried structures without disturbing the landscape. A drone-mounted remote sensing method called LIDAR—short for "Light Detection and Ranging"—shoots lasers at objects to generate data, which Lin visualizes with 3D mapping software. The results suggest what the ruins probably looked like when they were new.

Albert Lin and crew in Peru
Thomas Hardy, Adan Choqque Arce, Joseph Steel, Duncan Lees, Albert Lin, and Alonso Arroyo launch the LIDAR drone at Wat'a in Peru.
National Geographic

“It’s like a window into a world that we’ve never had before,” Lin tells Mental Floss. “It’s shooting millions of laser pulses per second through a distance of air. By digitally removing the top layer of everything above the ground—trees, brush, cacti—you’re washing away the past. All of the sudden you’re left with these fingerprints—experiments in how we organized ourselves through time.”

For the six-episode series, Lin and the expert storytelling team were dispatched to the South Pacific, the Middle East, the Andes, the Arctic, and other destinations. Lin explains that while most of the sites are known to archaeologists, they’ve never been so precisely mapped in three-dimensional detail.

In the first episode, Lin travels to Nan Madol, an enigmatic complex of temples and other structures on the Micronesian island of Pohnpei. With the help of local researchers and indigenous leaders, Lin and the team scan the ruins and digitally erase trees, water, and forest undergrowth to unveil the complex's former grandeur.

“Technology and innovation have always been that gateway to go beyond the threshold, and see what’s around the corner,” Lin says. “Seeing these worlds for the first time since they were left, it’s almost like reversing the burning of the library of Alexandria. We can take the synthesis of knowledge of all these watershed moments of our human journey, and imagine a better future.”

Lost Cities With Albert Lin premieres Sunday, October 20 at 10/9c and resumes on Monday, October 21 at 10/9c on National Geographic.

8 Ways Science Can Boost Your Halloween Fun

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Halloween is all about embracing the supernatural, but science shouldn't entirely fall by the wayside during the spookiest of holidays. Here are a few ways it can actually improve your holiday, from making trick-or-treating easier to fooling your brain into thinking you're eating tasty treats even though you're nibbling on candy cast-offs.

1. Slow the decomposition of your Halloween jack-o'-lantern.

A Halloween display of five jack-o-lanterns
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You don't have to be an expert gardener to keep your jack-o'-lantern looking fresh all Halloween season long. While scouting out pumpkins, pick hard, unblemished ones and steer clear of those with watery dark spots. These splotches indicate frost damage.

Hold off on carving until right before Halloween so your gourds won't rot—but if you can't resist, try squirting their exteriors with lemon juice after you're done slicing and dicing. The acid inhibits pumpkin enzymes, which react with oxygen and cause browning. A light misting of bleach solution will help keep fungus at bay. Some apply vegetable oil or Vaseline to prevent shriveling and drying. We experimented with various techniques in this video.

For extra TLC, you might even want to bring your jack-o'-lanterns in at night if temperatures dip; if you live in a hot and humid area, extend its life by placing it in the fridge overnight. Try using glow sticks or LED lights instead of flesh-singeing candles.

2. Use apps to plan a treat-or-treating route.

Three children in Halloween costumes trick-or-treating
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Thanks to technology, trick-or-treaters (and their hungry adult companions) can now scout out which neighbors are doling out the best candy and which are sticking with Tootsie Rolls, apples, and toothbrushes. Simply download the app for Nextdoor, the neighborhood-based social network, to check out an interactive "treat map" that lets users tag whether their home is handing out treats, and what that treat is.

Since safety is far more important than sugar, guardians should also consider adding a tracking app to their arsenal come Halloween, especially if their kid's venturing out alone. The Find My Family, Friends, Phone app gives the real-time locations of trick-or-treaters, provides alerts for when they turn home, and also comes with a "panic" button that provides emergency contact details when pressed.

3. Optimize your candy's flavor (even if it's SweeTarts).

Hard candies and gummies strewn across a table
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Not crazy about this year's Halloween loot? Fool yourself into thinking those black licorice pieces and peanut chews taste better than they actually do by eating them after you scarf down the chocolate and Sour Patch Kids. According to a 2012 study published in Psychological Science, being aware that these items of candy are your very last candies actually tricks the brain into appreciating them more (and thus thinking they're tastier than they really are).

Meanwhile, a 2013 study from the same journal found that creating a candy-eating ritual enhances flavor and overall satisfaction. Nibble the ridged edges off a Reese's peanut butter cup before tackling the creamy center, sort the M&Ms by color, and take your time unwrapping a chocolate bar.

4. Create a DIY fog machine with carbon.

Dry ice in a glass bowl
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Save money at Party City by creating your own fog machine at home. When dropped in water, dry ice—or frozen carbon dioxide—creates a gas that's a combination of carbon dioxide and water vapor, but looks like the fog you'd see rolling through a haunted graveyard [PDF].

5. Eat sort-of-heart-healthy Halloween candy.

A stack of dark chocolate chunks on a dark stone background
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Halloween candy isn't always bad for you. While shopping for this year's trick-or-treat bounty, steer clear of sugary confections and milk chocolate mini-bars. Opt for dark chocolate treats instead. Research suggests that our gut microbes ferment the antioxidants and fiber in cocoa, creating heart-healthy anti-inflammatory compounds. Plus, dark chocolate or cocoa also appears to help lower blood pressure for people with hypertension, decrease bad cholesterol, and stave off cardiovascular disease and diabetes, among other benefits.

6. Analyze data on Halloween candy trends and give the people what they want.

Lollipops
5second/iStock via Getty Images

Thanks to data science, you can make sure you're giving out the best treats on the block. Bulk candy retailer CandyStore.com combed through 10 years of data (2007 to 2016, with a particular focus on the months leading up to Halloween) to gauge America's top-selling sweets. They created an interactive map to display their results, which includes the top three most popular Halloween handouts in each state and Washington, D.C. Be prepared for plenty of stoop-side visitors and adorable photo ops.

7. Bake better Halloween treats with chemistry.

Frosted Halloween cookies shaped like ghosts and pumpkins
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Cooking is essentially chemistry—and depending on your technique, you can whip up chewy, fluffy, or decadent Halloween treats according to taste.

Folding chunks of chilled butter into your dough will give you thick, cake-like cookies, as will swapping baking soda for baking powder. When butter melts, its water converts into gas, which leaves lots of tiny holes. If the butter flecks in question are colder and larger, they'll leave bigger air pockets. As for the baking powder, it produces carbon dioxide gas both when it's mixed into the dough and when it's heated. For an extra boost in texture, you can also try adding more flour.

Prefer chewier cookies? Start out with melted butter in the dough, and stick with plain old baking soda.

And for extra-fragrant and flavorful baked goods, opt to use dark sugars—like molasses, honey, and brown sugar—because they're filled with glucose and fructose instead of plain old sucrose. As cookies bake, they undergo two processes: caramelization, in which the sugar crystals liquefy into a brown soup; and the Maillard reaction, a chemical reaction between the dough's proteins and amino acids (flour, egg, etc.) and the reducing sugars that causes tasty browning.

8. Take deep breaths to stay calm in haunted houses.

A brown-haired woman in a red polka dot blouse standing with a frightened expression next to a spider web.
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Halloween can be tough for people with anxiety or low thresholds for fear. While visiting a haunted house or watching a scary movie, remember to take deep breaths, which fends off the body's flight-or-fight response, and reframe your anxiety in your mind as "excitement." It's also a good idea to schedule spine-chilling activities after an activity that triggers feel-good endorphins—say, after a walk to check out your neighbors' awesome Halloween displays.

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