iStock
iStock

13 Things to Know About DNA Testing Kits

iStock
iStock

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.

nextArticle.image_alt|e
Apeel
New Plant-Based Coating Can Keep Your Avocados Fresh for Twice as Long
Apeel
Apeel

Thanks to a food technology startup called Apeel Sciences, eating fresh avocados will soon be a lot easier. The Bill Gates–backed company has developed a coating designed to keep avocados fresh for up to twice as long as traditional fruit, Bloomberg reports, and these long-lasting avocados will soon be available at 100 grocery stores across the Midwestern U.S. Thirty or so of the grocery stores involved in the limited rollout of the Apeel avocado will be Costcos, so feel free to buy in bulk.

Getting an avocado to a U.S. grocery store is more complicated than it sounds; the majority of avocados sold in the U.S. come from California or Mexico, making it tricky to get fruit to the Midwest or New England at just the right moment in an avocado’s life cycle.

Apeel’s coating is made of plant material—lipids and glycerolipids derived from peels, seeds, and pulp—that acts as an extra layer of protective peel on the fruit, keeping water in and oxygen out, and thus reducing spoilage. (Oxidation is the reason that your sliced avocados and apples brown after they’ve been exposed to the air for a while.) The tasteless coating comes in a powder that fruit producers mix with water and then dip their fruit into.

A side-by-side comparison of a coated and uncoated avocado after 30 days, with the uncoated avocado looking spoiled and the coated one looking fresh
Apeel

According to Apeel, coating a piece of produce in this way can keep it fresh for two to three times longer than normal without any sort of refrigeration of preservatives. This not only allows consumers a few more days to make use of their produce before it goes bad, reducing food waste, but can allow producers to ship their goods to farther-away markets without refrigeration.

Avocados are the first of Apeel's fruits to make it to market, but there are plans to debut other Apeel-coated produce varieties in the future. The company has tested its technology on apples, artichokes, mangos, and several other fruits and vegetables.

[h/t Bloomberg]

nextArticle.image_alt|e
iStock
15 Facts About the Summer Solstice
iStock
iStock

It's the longest day of the year in the Northern Hemisphere, so soak up some of those direct sunrays (safely, of course) and celebrate the start of summer with these solstice facts.

1. THIS YEAR IT'S JUNE 21.

June 21 date against a yellow background
iStock

The summer solstice always occurs between June 20 and June 22, but because the calendar doesn't exactly reflect the Earth's rotation, the precise time shifts slightly each year. For 2018, the sun will reach its greatest height in the sky for the Northern Hemisphere on June 21 at 6:07 a.m. Eastern Time.

2. THE SUN WILL BE DIRECTLY OVERHEAD AT THE TROPIC OF CANCER.

A vintage mapped globe showing the Tropic of Cancer
iStock

While the entire Northern Hemisphere will see its longest day of the year on the summer solstice, the sun is only directly overhead at the Tropic of Cancer (23 degrees 27 minutes north latitude).

3. THE NAME COMES FROM THE FACT THAT THE SUN APPEARS TO STAND STILL.

Stonehenge at sunrise.
CARL DE SOUZA, AFP/Getty Images

The term "solstice" is derived from the Latin words sol (sun) and sistere (to stand still), because the sun's relative position in the sky at noon does not appear to change much during the solstice and its surrounding days. The rest of the year, the Earth's tilt on its axis—roughly 23.5 degrees—causes the sun's path in the sky to rise and fall from one day to the next.

4. THE WORLD'S BIGGEST BONFIRE WAS PART OF A SOLSTICE CELEBRATION.

A large bonfire
iStock

Celebrations have been held in conjunction with the solstice in cultures around the world for hundreds of years. Among these is Sankthans, or "Midsummer," which is celebrated on June 24 in Scandinavian countries. In 2016, the people of Ålesund, Norway, set a world record for the tallest bonfire with their 155.5-foot celebratory bonfire.

5. THE HOT WEATHER FOLLOWS THE SUN BY A FEW WEEKS.

Colorful picture of the sun hitting ocean waves.
iStock

You may wonder why, if the solstice is the longest day of the year—and thus gets the most sunlight—the temperature usually doesn't reach its annual peak until a month or two later. It's because water, which makes up most of the Earth's surface, has a high specific heat, meaning it takes a while to both heat up and cool down. Because of this, the Earth's temperature takes about six weeks to catch up to the sun.

6. THOUSANDS OF PEOPLE GATHER AT STONEHENGE TO CELEBRATE.

Rollo Maughfling, the Archdruid of Glastonbury and Stonehenge, conducts a Solstice celebration service for revelers as they wait for the midsummer sunrise at Stonehenge on June 21, 2012, near Salisbury, England.
Rollo Maughfling, the Archdruid of Glastonbury and Stonehenge, conducts a Solstice celebration service for revelers as they wait for the midsummer sunrise at Stonehenge on June 21, 2012, near Salisbury, England.
Matt Cardy, Getty Images

People have long believed that Stonehenge was the site of ancient druid solstice celebrations because of the way the sun lines up with the stones on the winter and summer solstices. While there's no proven connection between Celtic solstice celebrations and Stonehenge, these days, thousands of modern pagans gather at the landmark to watch the sunrise on the solstice.

7. PAGANS CELEBRATE THE SOLSTICE WITH SYMBOLS OF FIRE AND WATER.

Arty image of fire and water colliding.
iStock

In Paganism and Wicca, Midsummer is celebrated with a festival known as Litha. In ancient Europe, the festival involved rolling giant wheels lit on fire into bodies of water to symbolize the balance between fire and water.

8. IN ANCIENT EGYPT, THE SOLSTICE HERALDED THE NEW YEAR.

Stars in the night sky.
iStock

In Ancient Egypt, the summer solstice preceded the appearance of the Sirius star, which the Egyptians believed was responsible for the annual flooding of the Nile that they relied upon for agriculture. Because of this, the Egyptian calendar was set so that the start of the year coincided with the appearance of Sirius, just after the solstice.

9. THE ANCIENT CHINESE HONORED THE YIN ON THE SOLSTICE.

Yin and yang symbol on textured sand.
iStock

In ancient China, the summer solstice was the yin to the winter solstice's yang—literally. Throughout the year, the Chinese believed, the powers of yin and yang waxed and waned in reverse proportion to each other. At the summer solstice, the influence of yang was at its height, but the celebration centered on the impending switch to yin. At the winter solstice, the opposite switch was honored.

10. IN ALASKA, THE SOLSTICE IS CELEBRATED WITH A MIDNIGHT BASEBALL GAME.

Silhouette of a baseball player.
iStock

Each year on the summer solstice, the Alaska Goldpanners of Fairbanks celebrate their status as the most northerly baseball team on the planet with a game that starts at 10:00 p.m. and stretches well into the following morning—without the need for artificial light—known as the Midnight Sun Game. The tradition originated in 1906 and was taken over by the Goldpanners in their first year of existence, 1960.

11. THE EARTH IS ACTUALLY AT ITS FARTHEST FROM THE SUN DURING THE SOLSTICE.

The Earth tilted on its axis.
iStock

You might think that because the solstice occurs in summer that it means the Earth is closest to the sun in its elliptical revolution. However, the Earth is actually closest to the sun when the Northern Hemisphere experiences winter and is farthest away during the summer solstice. The warmth of summer comes exclusively from the tilt of the Earth's axis, and not from how close it is to the sun at any given time. 

12. IRONICALLY, THE SOLSTICE MARKS A DARK TIME IN SCIENCE HISTORY.

Galileo working on a book.
Hulton Archive, Getty Images

Legend has it that it was on the summer solstice in 1633 that Galileo was forced to recant his declaration that the Earth revolves around the Sun; even with doing so, he still spent the rest of his life under house arrest.

13. AN ALTERNATIVE CALENDAR HAD AN EXTRA MONTH NAMED AFTER THE SOLSTICE.

Pages of a calendar
iStock

In 1902, a British railway system employee named Moses B. Cotsworth attempted to institute a new calendar system that would standardize the months into even four-week segments. To do so, he needed to add an extra month to the year. The additional month was inserted between June and July and named Sol because the summer solstice would always fall during this time. Despite Cotsworth's traveling campaign to promote his new calendar, it failed to catch on.

14. IN ANCIENT GREECE, THE SOLSTICE FESTIVAL MARKED A TIME OF SOCIAL EQUALITY.

Ancient Greek sculpture in stone.
iStock

The Greek festival of Kronia, which honored Cronus, the god of agriculture, coincided with the solstice. The festival was distinguished from other annual feasts and celebrations in that slaves and freemen participated in the festivities as equals.

15. ANCIENT ROME HONORED THE GODDESS VESTA ON THE SOLSTICE.

Roman statue of a vestal virgin
iStock

In Rome, midsummer coincided with the festival of Vestalia, which honored Vesta, the Roman goddess who guarded virginity and was considered the patron of the domestic sphere. On the first day of this festival, married women were allowed to enter the temple of the Vestal virgins, from which they were barred the rest of the year.

A version of this list originally ran in 2015.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios