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With a mortar and pestle, Christy Till blends together the makings of a distant planet. In her geology lab at Arizona State University in Tempe, Till carefully measures out powdered minerals, tips them into a metal capsule and bakes them in a high-pressure furnace that can reach close to 35,000 times Earth’s atmospheric pressure and 2,000° Celsius.

In this interplanetary test kitchen, Till and colleagues are figuring out what might go into a planet outside of our solar system.

“We’re mixing together high-purity powders of silica and iron and magnesium in the right proportions to make the composition we want to study,” Till says. She’s starting with the makings of what might resemble a rocky planet that’s much different from Earth. “We literally make a recipe.”
Scientists have a few good ideas for how to concoct our own solar system. One method: Mix up a cloud of hydrogen and helium, season generously with oxygen and carbon, and sprinkle lightly with magnesium, iron and silicon. Condense and spin until the cloud forms a star surrounded by a disk. Let rest about 10 million years, until a few large lumps appear. After about 600 million years, shake gently.

But that’s only one recipe in the solar systems cookbook. Many of the planets orbiting other stars are wildly different from anything seen close to home. As the number of known exoplanets has climbed — 3,717 confirmed as of April 12 — scientists are creating new recipes.

Seven of those exoplanets are in the TRAPPIST-1 system, one of the most exciting families of planets astronomers have discovered to date. At least three TRAPPIST-1 planets might host liquid water on their surface, making them top spots to look for signs of life (SN: 12/23/17, p. 25).

Yet those planets shouldn’t exist. Astronomers calculated that the small star’s preplanet disk shouldn’t have contained enough rocky material to make even one Earth-sized orb, says astrophysicist Elisa Quintana of NASA’s Goddard Space Flight Center in Greenbelt, Md. Yet the disk whipped up seven.
TRAPPIST-1 is just one of the latest in a long line of rule breakers. Other systems host odd characters not seen in our solar system: super-Earths, mini-Neptunes, hot Jupiters and more. Many exoplanets must have had chaotic beginnings to exist where we find them.

These oddballs raise exciting questions about how solar systems form. Scientists want to know how much of a planet’s ultimate fate depends on its parent star, which ingredients are essential for planet building and which are just frosting on the planetary cake.
NASA’s Transiting Exoplanet Survey Satellite, or TESS, which launched April 18, should bring in some answers. TESS is expected to find thousands more exoplanets in the next two years. That crowd will help illuminate which planetary processes are the most common — and will help scientists zero in on the best planets to check for signs of life.
Beyond the bare necessities
All solar system recipes share some basic elements. The star and its planets form from the same cloud of gas and dust. The densest region of the cloud collapses to form the star, and the remaining material spreads itself into a rotating disk, parts of which will eventually coalesce into planets. That similarity between the star and its progeny tells Till and other scientists what to toss into the planetary stand mixer.

“If you know the composition of the star, you can know the composition of the planets,” says astronomer Johanna Teske of the Carnegie Observatories in Pasadena, Calif. A star’s composition is revealed in the wavelengths of light the star emits and absorbs.

When a planet is born can affect its final makeup, too. A gas giant like Jupiter first needs a rocky core about 10 times Earth’s mass before it can begin gobbling up gas. That much growth probably happens well before the disk’s gas disappears, around 10 million years after the star forms. Small, rocky planets like Earth probably form later.

Finally, location matters. Close to the hot star, most elements are gas, which is no help for building planets from scratch. Where the disk cools toward its outer edge, more elements freeze to solid crystals or condense onto dust grains. The boundary where water freezes is called the snow line. Scientists thought that water-rich planets must either form beyond their star’s snow line, where water is abundant, or must have water delivered to them later (SN: 5/16/15, p. 8). Giant planets are also thought to form beyond the snow line, where there’s more material available.

But the material in the disk might not stay where it began, Teske says. “There’s a lot of transport of material, both toward and away from the star,” she says. “Where that material ends up is going to impact whether it goes into planets and what types of planets form.” The amount of mixing and turbulence in the disk could contribute to which page of the cookbook astronomers turn to: Is this system making a rocky terrestrial planet, a relatively small but gaseous Neptune or a massive Jupiter?
Some like it hot
Like that roiling disk material, a full-grown planet can also travel far from where it formed.

Consider “Hoptunes” (or hot Neptunes), a new class of planets first named in December in Proceedings of the National Academy of Sciences. Hoptunes are between two and six times Earth’s size (as measured by the planet’s radius) and sidled up close to their stars, orbiting in less than 10 days. That close in, there shouldn’t have been enough rocky material in the disk to form such big planets. The star’s heat should mean no solids, just gases.

Hoptunes share certain characteristics — and unanswered questions — with hot Jupiters, the first type of exoplanet discovered, in the mid-1990s.

“Because we’ve known about hot Jupiters for so long, some people kind of think they’re old hat,” says astronomer Rebekah Dawson of Penn State, who coauthored a review about hot Jupiters posted in January at arXiv.org. “But we still by no means have a consensus about how they got so close to their star.”

Since the first known hot Jupiter, 51 Pegasi b, was confirmed in 1995, two explanations for that proximity have emerged. A Jupiter that formed past the star’s snow line could migrate in smoothly through the disk by trading orbital positions with the disk material itself in a sort of gravitational do-si-do. Or interactions with other planets or a nearby star could knock the planet onto an extremely elliptical or even backward orbit (SN Online: 11/1/13). Over time, the star’s gravity would steal energy from the orbit, shrinking it into a tight, close circle. Dawson thinks both processes probably happen.

Hot Jupiters are more common around stars that contain a lot of elements heavier than hydrogen and helium, which astronomers call metals, astronomer Erik Petigura of Caltech and colleagues reported in February in the Astronomical Journal. High-metal stars probably form more planets because their disks have more solids to work with. Once a Jupiter-sized planet forms, a game of gravitational billiards could send it onto an eccentric orbit — and send smaller worlds out into space. That fits the data, too; hot Jupiters tend to lack companion worlds.

Hoptunes follow the same pattern: They prefer metal-rich stars and have few sibling planets. But Hoptunes probably arrived at their hot orbits later in the star’s life. Getting close to a young star, a Hoptune would risk having its atmosphere stripped away. “They’re sort of in the danger zone,” Dawson says. Since Hoptunes do, in fact, have atmospheres, they were probably knocked onto an elliptical, and eventually close-in, orbit later.

One striking exception to the hot loner rule is WASP-47b, a hot Jupiter with two nearby siblings between the sizes of Earth and Neptune. That planet is one reason Dawson thinks there’s more than one way to cook up a hot Jupiter.

Rock or gas
Hot Jupiters are so large that astronomers assume these exoplanets have thick atmospheres. But it’s harder to tell if a smaller planet is gassy like Neptune or rocky like Earth.

To make a first guess at a planet’s composition, astronomers need to know the planet’s size and mass. Together, those numbers yield the planet’s density, which gives a sense of how much of the planet is solid like rock or diffuse like an atmosphere.
The most popular planet detection strategies each measure one of those factors. The transit method, used by the Kepler space telescope, watches a star wink as the planet passes in front. Comparing the star’s light before and during the transit reveals the planet’s size. The radial velocity method, used with telescopes on the ground, watches the star wobble in response to a planet’s gravity, which reveals the planet’s mass.

Most of the stars observed by Kepler are too far away and too dim for direct, accurate measures of planet masses. But astronomers have inferred a size cutoff for rocky planets. Last June, researchers analyzing the full Kepler dataset noticed a surprising lack of planets between 1.5 and two times Earth’s size and suggested those 1.5 times Earth’s radius or smaller are probably rocky; two to 3.5 times Earth’s radius are probably gassy (SN Online: 6/19/17).

Dozens more planets have had their masses inferred indirectly, mostly those in multiplanet systems where astronomers can observe how planets tug on one another. From what astronomers can tell, super-Earths — planets between one and about 10 times Earth’s mass — come in a wide range of compositions.

The Kepler mission is about to end, as the spacecraft’s fuel is running out. TESS will pick up where Kepler leaves off. The new planet-hunting space telescope will revolutionize the study of super-Earth densities. It will scan 85 percent of the sky for bright, nearby stars to pick out the best planets for follow-up study. As part of its primary mission, TESS will find at least 50 planets smaller than Neptune that can have their masses measured precisely, too. “Having masses … will help us understand the compositions,” says Quintana, a TESS team member. “We can see: Is there a true transition line where planets go rocky to gaseous? Or is it totally random? Or does it depend on the star?”

Star power
All kinds of planets’ fates do, in fact, depend on the stars, Petigura’s recent work suggests. In a February report in the Astronomical Journal, he and colleagues measured the metal contents of 1,305 planet-hosting stars in Kepler’s field of view.

The researchers learned that large planets and close-in planets — with orbital periods of 10 days or less — are more common around metal-rich stars. But the team was surprised to find that small planets and planets that orbit far from their stars show up around stars of all sorts of compositions. “They form efficiently everywhere,” Petigura says.

That could mean that metal-rich stars had disks that extended closer to the stars. With enough material close to the star, hot super-Earths could have formed where they currently spin. The existence of hot super-Earths might even suggest that hot Jupiters can form close to the star after all. A super-Earth or mini-Neptune could represent the core of what was once a hot Jupiter that didn’t quite gather enough gas before the disk dissipated, or whose atmosphere was blown off by the star (SN Online: 10/31/17).

Weird water
Some scientists are looking to stars to reveal what’s inside a planet. The help is welcome because density is a crude measure for understanding what a planet is made of. Planets with the same mass and radius can have very different compositions and natures — look at hellish Venus and livable Earth.

Take the case of TRAPPIST-1, which has seven Earth-sized worlds and is 39 light-years away. Astronomers are anxious to check at least three of the planets for signs of life (SN: 12/23/17, p. 25). But those planets might be so waterlogged that any signs of life would be hard to detect, says exogeologist Cayman Unterborn of Arizona State. So much water would change a planet’s chemistry in a way that makes it hard to tell life from nonlife. Based on the planets’ radii (measured by their transits) and their masses (measured by their gravitational influence on one another), Unterborn and colleagues used density to calculate a bizarre set of interiors for the worlds, which the team reported March 19 in Nature Astronomy.

The TRAPPIST-1 planets have low densities for their size, Unterborn says, suggesting that their masses are mostly light material like water ice. TRAPPIST-1b, the innermost planet, seems to be 15 percent water by mass (Earth is less than 0.1 percent water). The fifth planet out, TRAPPIST-1f, may be at least half water by mass. If the planet formed with all that water already in it, it would have had 1,000 Earth oceans’ worth of water. That amount of water would compress into exotic phases of ice not found at normal pressures on Earth. “That is so much water that the chemistry of how that planet crystallized is not something we have ever imagined,” Unterborn says.
But there’s a glitch. Unterborn’s analysis was based on the most accurate published masses for the TRAPPIST-1 worlds at the time. But on February 5, the same day his paper was accepted in Nature Astronomy, a group led by astronomer Simon Grimm of the University of Bern in Switzerland posted more precise mass measurements at arXiv.org. Those masses make the soggiest planets look merely damp.

Clearly, Unterborn says, density is not destiny. Studying a planet based on its mass and radius has its limits.

Looking deeper
As a next step, Unterborn and colleagues have published a series of papers suggesting how stellar compositions can tell the likelihood that a group of planets have plate tectonics, or how much oxygen the planet atmospheres may have. Better geologic models may ultimately help reveal if a single planet is habitable.

But Unterborn is wary of translating composition from a star to any individual planet — existing geochemical models aren’t good enough. The recent case of K2-229b makes that clear. Astronomer Alexandre Santerne of the Laboratory of Astrophysics of Marseille in France and colleagues recently tried to see if a star’s composition could describe the interior of its newly discovered exoplanet, K2-229b. The team reported online March 26 in Nature Astronomy that the planet has a size similar to Earth’s but a makeup more like Mercury’s: 70 percent metallic core, 30 percent silicate mantle by mass. (The researchers nicknamed the planet Freddy, for Queen front man Freddie Mercury, Santerne wrote on Twitter.) That composition is not what they’d expect from the star alone.
Geologic models need to catch up quickly. After TESS finds the best worlds for follow-up observations, the James Webb Space Telescope, due to launch in 2020, will search some of those planets’ atmospheres for signs of life (SN: 4/30/16, p. 32). For that strategy to work, Unterborn says, scientists need a better read on the exoplanet cookbook.

Christy Till’s pressure-packed test kitchen may help. Till is primarily a volcanologist who studies how magma erupting onto Earth’s surface can reveal conditions in Earth’s interior. “The goal is to start doing that for exoplanets,” she says.

Till and colleagues are redoing some foundational experiments conducted for Earth 50 years ago but not yet done for exoplanets. The experiments predict which elements can go into planets’ mantles and cores, and which will form solid crusts. (Early results that Till and grad student Mitchell Phillips presented in December in New Orleans at the American Geophysical Union meeting suggest that multiplying the sun’s magnesium-to-silicon ratio by 1.33 still bakes a rocky planet, but with a different flavored crust than Earth’s.)

Till uses three piston cylinders to squash and singe synthetic exoplanets for 24 hours to see what minerals form and melt at different pressures and temperatures. The results may help answer questions like what kind of lava would erupt on a planet’s surface, what would the crust be made of and what gases might end up in the planet’s atmosphere.

It’s early days, but Till’s recipe testing may mean scientists won’t have to wait decades for telescopes to get a close enough look at an exoplanet to judge how much like home it really is. With new cookbook chapters, Unterborn says, “we can figure out which stars are the best places to build an Earth.”

Language learning isn’t kid stuff anymore. In fact, it never was, a provocative new study concludes.

A crucial period for learning the rules and structure of a language lasts up to around age 17 or 18, say psychologist Joshua Hartshorne of MIT and colleagues.

Previous research had suggested that grammar-learning ability flourished in early childhood before hitting a dead end around age 5. If that were true, people who move to another country and try to learn a second language after the first few years of life should have a hard time achieving the fluency of native speakers.

But that’s not so, Hartshorne’s team reports online May 2 in Cognition. In an online sample of unprecedented size, people who started learning English as a second language in an English-speaking country by age 10 to 12 ultimately mastered the new tongue as well as folks who had learned English and another language simultaneously from birth, the researchers say. Both groups, however, fell somewhat short of the grammatical fluency displayed by English-only speakers.
After ages 10 to 12, new-to-English learners reached lower levels of fluency than those who started learning English at younger ages because time ran out when their grammar-absorbing ability plummeted starting around age 17.

In another surprise, modest amounts of English learning among native and second-language speakers continued until around age 30, the investigators found, although most learning happened in the first 10 to 20 years of life.

Earlier investigations have included too few monolingual and bilingual participants — typically no more than 250 per study — to reveal the entire timeline of grammar learning, Hartshorne says. Aiming for a sample of tens of thousands of volunteers, he began by contacting friends on Facebook to take an online English grammar quiz, which used a person’s responses to guess his or her native language and dialect of English. After completing the quiz, volunteers filled out a questionnaire asking where they had lived, languages they had spoken from birth, the age at which they began learning English and the number of years they had lived in an English-speaking country.

As Hartshorne had hoped, the quiz was shared widely on Facebook and other social media, allowing the researchers to analyze responses of 669,498 native and nonnative English speakers. Statistical calculations focused on estimating at what ages people with varying amounts of experience speaking English reached peak grammar ability.

Researchers who study language learning regard the new study as intriguing, but preliminary. “I see this as a first foray, a blast of data that, while powerful, lacks precision,” says psycholinguist David Barner of the University of California, San Diego.

For instance, Hartshorne’s team can’t yet say that language skill develops along a single timeline. Different elements of grammar, such as using correct word order or subjects and verbs that agree with one another, might be learned at different rates, Barner says. It’s also unclear whether the responses of volunteers to an online, 132-item grammar test reflect how well or poorly they actually speak English, he says.

Because the researchers did not test children younger than age 7, the team couldn’t adequately assess how long it really takes to learn English, says psycholinguist Elissa Newport of Georgetown University in Washington D.C. The researchers claim that learning takes a total of 30 years, leading to their estimate that the critical period of learning comes to an end at age 17. But Newport emphasizes that hundreds of previous studies, including hers, have found that native language learning is largely done by age 7 (SN: 7/28/01, p. 54), and second-language learning proceeds best for those who start by around age 5.
What’s more, language learning involves more than a crucial period for acquiring grammar, cautions linguist David Birdsong of the University of Texas at Austin. For instance, growing up speaking two languages at once puts still poorly understood strains on the ability to grasp grammar, he says.

In the new study, people who were bilinguals from birth fell short of peak English grammar scores achieved by English-only speakers. That’s consistent with evidence that bilinguals cannot easily turn off one language while speaking another, Birdsong says. Interactions between tongues spoken by one person may slightly depress how much can be learned about both languages, even if bilingual communication still reaches high levels, he suggests.

A search for plasma precipitation in the sun’s atmosphere reveals that the rain turns up in unexpected places. That discovery might mean the rain can fall as a fine mist as well as a shower, new data suggest. Ultimately, tracing the movement of this plasma could help solve the mystery of why the solar atmosphere, or corona, is so hot.

The sun has rainfall similar to Earth’s, but with plasma instead of water. When hot plasma moves into a cooler part of the corona, it condenses and falls back toward the solar surface, just as hot air condenses into clouds that form water droplets that rain down on Earth. “The physics is literally the same,” says solar physicist Emily Mason of the Catholic University of America in Washington, D.C., who presented the new observations of coronal rain at the Triennial Earth-Sun Summit on May 22.
Scientists have seen coronal rain before, mostly as showers in solar regions associated with flares. But it can happen anywhere in the corona where temperatures go from higher to lower, Mason says. Theoretical studies by others, including her colleague Spiro Antiochos of NASA’s Goddard Space Flight Center in Greenbelt, Md., suggested that tall streamers, which can stretch up to 6 solar radii above the sun’s surface, could be hotter at their base than their tip and so should be full of rain (SN Online: 8/17/17).

“My job was to find it,” Mason says. So she searched for bright blobs of plasma falling within the tall streamers in videos recorded in extreme ultraviolet light by NASA’s Solar Dynamics Observatory — but spotted none.

She did find rain showers, however, in much shorter loops called null-point topologies, which stretch only to about 0.1 solar radii above the surface. “These things rain like crazy,” she says. Coronal rain fell in one of these smaller loops for 30 hours.
The finding is surprising because shorter loops should have less of a temperature difference from bottom to top than the tall streamers, making such precipitation more difficult. What’s more, Mason thinks the shorter loops don’t actually rain more than streamers, but that the plasma blobs in such loops might be larger and easier to see. In tall streamers, because the temperature changes more gradually, blobs would end up being smaller — possibly as small as sand grains. “It’s there, but it’s invisible,” she argues.

Mason later found much dimmer rain in mid-sized pseudostreamers, which supports that idea. Current telescopes can’t see the smallest blobs, but the Daniel K. Inouye Solar Telescope under construction in Hawaii may be able to.

One long-standing solar mystery is that temperatures in the corona are millions of degrees higher than those at the sun’s surface (SN Online: 8/20/17). Scientists think the extra heat may come from an unknown, continuous source — as if the corona were sitting on a hot stovetop — or from a bunch of small, short bursts of energy (SN: 5/30/15, p. 7). The new rain results support the stovetop idea because that would set up the necessary temperature differences in the short loops, says solar physicist Nicholeen Viall of NASA Goddard, who was not involved in the discovery.

“The fact that the rain is there puts limits on how coronal heating could have happened,” Viall says. “The fact that she found it is pretty important.”

Like humans, African apes called bonobos may treat birth as a social event with a serious purpose.

In three recorded instances in captivity, female bonobos stood close by and provided protection and support to a bonobo giving birth to a healthy infant. Female bystanders also gestured as if ready to hold an infant before it was born, or actually held one as it was born, scientists report online May 9 in Evolution and Human Behavior. Ethologist Elisa Demuru of the Natural History Museum of the University of Pisa in Italy and colleagues filmed these incidents in 2009, 2012 and 2014 at two European primate parks where the apes roam freely through forested areas.

These observations, along with a 2014 report of wild bonobos behaving similarly, challenge an influential idea that human females, unlike other primates, receive birth assistance. Scientists had proposed that the perils of passing a baby through the relatively narrow human birth canal called for help from others. But bonobos can safely give birth on their own, so something else is at work here, Demuru and colleagues suspect. Comparably high levels of sociability among female bonobos and among women may instead explain why helpers assemble as a pregnant individual nears delivery.

Chimpanzees, close cousins of bonobos, are a different story. Female chimps are more competitive and maintain weaker social bonds than female bonobos or humans do. No chimps have been spotted helping or hanging out near a peer about to give birth.

Research on birth practices in wild and captive ape communities remains in its infancy, the investigators say.

Michael Douglas, a new resident of southern Maryland, credits genetic testing for helping him find his heritage — and a family he knew very little about.

Douglas, 43, is adopted. He knew his birth mother’s name and had seen a birth certificate stating his birth name: Thomas Michael McCarthy. Over the years, Douglas had tried off and on to find his birth family, mostly by looking for his mother’s name, Deborah Ann McCarthy, in phone books and calling the numbers. “I think I must have broken up a lot of marriages,” he laughs.

His search gained urgency in the last five years as he battled a life-threatening illness. “We planned my funeral three times,” he says. Douglas has a genetic disease called Ehlers-Danlos syndrome, caused by a variant in a gene that helps build the body’s connective tissue. His stretchy skin and hyperflexible joints are characteristic of the disease.

“As a kid, I was always dislocating something,” he says. His blood vessels don’t constrict properly to maintain his blood pressure, so Douglas sometimes faints when he stands up. For five years, he has had a constant migraine. Headaches are typical of about a third of people with Ehlers-Danlos. On top of that, he has B cell lymphoma. “I feel like I have the flu every day,” he says. It was time, he decided, to track down his birth family and learn more about his medical history.

In June 2017, Douglas flew to Ireland on what he calls his “death trip.” He wanted to see the land of his McCarthy ancestors. He chose Fethard, because the walled medieval town has a pub called McCarthy’s. (Douglas learned later that he and the pub owner are related.) His health improved during the visit, which he attributes to Ireland’s cool weather. When he returned to Phoenix, where he and his adopted family lived, he had new resolve to find his birth family.

“That’s it,” he decided. “I need my DNA run to find out who I am.” He sent his DNA to three testing companies: Family Tree DNA, AncestryDNA and MyHeritage. With his results plus sleuthing of genealogical records by some helpful strangers, Douglas found his biological family last November and dove headfirst into a new life.

In February, he moved from Phoenix to Maryland to help care for his biological mother as she recovers from a stroke. The new family dynamic hasn’t been easy, but Douglas has bonded with one of his two biological brothers. “And I have a relationship with my ancestors that I did not know before.” He is pleased to find that he resembles his great-grandfather Thomas Rodda, a bicycle maker. Douglas himself is a Star Wars costume maker.
Adoptees like Douglas and birth parents looking for children they gave up often use commercial DNA tests in hopes of reconnecting, says Drew Smith, a genealogical librarian at the University of South Florida in Tampa. Many states make it difficult for adoptees to get birth certificates or other documents that could help them track down birth families. DNA tests are “an end run around the documentation problem,” Smith says.

But the pool of people looking for their genetic roots is much larger. AncestryDNA, the ancestry testing service with the biggest customer base, has persuaded about 10 million people to take its DNA test. 23andMe, Living DNA, Family Tree DNA, MyHeritage, National Geographic’s Geno 2.0 and others also offer customers a chance to use genetics to connect with living relatives and with families’ pasts. A few companies even give hints about ties that go back to Neandertals (SN: 11/11/17, p. 10). But such testing services may not be able to tell you as much about who you are and where your family came from as they claim.
False precision
I got my DNA tested for this multipart reporting project. My assignment was to investigate the science behind DNA testing (SN: 6/9/18, p. 20), but it was also a welcome excuse to learn more about my family’s history.

I already knew a lot about three branches of my family tree. Based on birth and death records, plus census and other documents, most of my family stems from England and Germany. But I dreamed of connecting to relatives on the Hungarian branch, which I knew less about. So I sent saliva or cheek swabs to a handful of testing companies.

My ethnicity estimates were all over the European map. Generally, estimates are most accurate on the broad continental scale. All of the companies agree that my heritage is overwhelmingly European. But that’s where the consensus ends. Even the companies that limit their estimates to broad swaths of the continent told different stories. National Geographic’s Geno 2.0 says that I am 45 percent Southwestern European. Veritas Genetics puts my Southwestern European heritage at only 4 percent and tells me I’m mostly (91.1 percent) north-central European.

The companies that try to dig down to the country level see their confidence in the results go down, but that doesn’t stop them from making very specific estimates. In most reports, the main results given are at the lower end of the confidence scale. 23andMe, for instance, says it has 50 percent statistical confidence in the ethnicity results.

Along with the wide variations between companies, the estimates often didn’t match what I know about my family tree. 23andMe says I’m 16.6 percent Scandinavian. When I sent raw data from 23andMe to MyHeritage to do its own analysis, that company reported no Scandinavian ancestry in my background; it said I’m 16.9 percent Italian. As far as I know, I have no ancestors from Italy or Scandinavia.

Only 23andMe called out my German heritage, though the company lumped it in with French for a total of 18.8 percent. Hungarian is not specifically identified in any company’s estimates. I can only guess that 23andMe’s 3.9 percent Eastern European and 0.3 percent Balkan findings cover that part of my ancestry. Both 23andMe and AncestryDNA say that I have Ashkenazi Jewish heritage. News to me.

Multiple companies agree that a sizable chunk of my heritage is from the British Isles. But even in that, estimates run from 23andMe’s 26.6 percent British and Irish, to Living DNA’s calculation that 60.3 percent of my DNA comes from Great Britain and Ireland, to MyHeritage’s even higher 78.7 percent.

When I shared these inconsistencies with Deborah Bolnick, an anthropological geneticist at the University of Texas at Austin, I could practically hear her shaking her head over the phone.

“They present these very specific, precise numbers down to the decimal point. But it’s a false precision,” Bolnick says. “The tests that are available may not be as nuanced, sensitive and fine scaled as they are presented.”
Checking references
Ethnicity estimates come from comparing patterns of genetic variants — often called single nucleotide polymorphisms, or SNPs — in your DNA with the SNP patterns of pools of people from particular geographic locations. As a way to confirm that a pool solidly represents a place, companies generally require that the people in these pools, known as the reference populations, have four grandparents who were also born in that location. Many of the companies draw reference population DNA samples from people in large public databases compiled by the 1000 Genomes Project, a catalog of genetic variation of thousands of people around the world, and from other studies. Some companies supplement their databases by testing more people in particular parts of the world. So the mixes in reference populations differ across companies.

Who the companies say you are depends in large part on those reference populations, Bolnick says. For instance, you may carry a pattern of SNPs found in people in both southern France and in Italy. If, by chance, the French people a company sampled had that SNP pattern but none of the Italians in the company’s database did, “they may infer that you have French ancestors and not Italian because of who they do and do not have in their database,” Bolnick explains.

Drilling down to tell customers which country or which part of a country their ancestors called home requires sampling many people in those countries, together with more sophisticated math to detect slight differences in the patterns. By looking at more than SNP patterns, Living DNA provides ethnicity estimates down to subregions of the United Kingdom and Ireland. The company analyzes how different stretches of DNA are connected to each other, says David Nicholson, the company’s cofounder and managing director.

It’s a bit like regional differences in the way people in southwest England assemble scones, cream and jam for cream teas. “In Devon you have a scone, cream and then you have jam,” Nicholson says. “In Cornwall you have a scone, jam, cream, so you have them in a different order. Most DNA tests just tell you that you have a scone, jam and cream so you’re from the U.K.” But because his company looks at the order of the DNA ingredients, Nicholson claims his results can tell customers what part of the British Isles was their ancestral home.
Dividing lines
In reality, what the companies can say with certainty is that you share common DNA patterns with people living in those places today. But your ancestors may not always have lived where their descendants do now, Bolnick says. People move around, which muddies the waters.

For many Americans, some branches of their families may be recent immigrants, while other branches may have deep roots in American soil. Two branches of my family came to Massachusetts and Maryland from England in the 1600s. One branch moved from Germany to Nebraska in the late 1800s, and my Hungarian great-grandparents arrived in 1905.

Most Americans who get tested want to know about family from before the big move to the United States, says human geneticist Joe Pickrell, chief executive of DNA testing company Gencove. But the answer isn’t simple. DNA is a record of thousands of ancestors stretching back deep in time, each from a slightly different place. How companies sort out time and place may produce different ancestry estimates, Pickrell says.
Take a stretch of DNA containing a particular SNP pattern. “Today it may be found in you in the United States and in relatives in England and Germany, but it could be that 500 years ago your shared ancestor lived in Italy,” Bolnick explains. Going further back in time, that stretch of DNA may look like it came from Romania, Mongolia and Siberia. “As people move and the genes that they have move with them, it’s going to change what those geographic ancestries look like,” she says.

Given the timing of my family’s migrations, I would have expected a much bigger percentage of my ethnicity to come from the newer immigrants. I thought my British ancestry would have been diluted after hundreds of years in America, but I guess not.

Further complicating matters, most people think of their ancestry as coming from particular countries, but genetics cuts across and transcends national borders, Bolnick says. In reality, those categories are not genetic, they’re sociopolitical and historic.

Smith, in South Florida, agrees: “From a DNA perspective, it’s hard to tell a French person from a German person.”

Missing groups
And some groups, including aboriginal populations in Australia and big parts of Africa and Asia, are mostly absent from companies’ databases. The same goes for Native Americans, whose samples in public databases are small, and in some cases, were collected by questionable means, says Krystal Tsosie, a geneticist at Vanderbilt University in Nashville.
She’s talking about “vampire projects,” in which geneticists swooped in to draw blood from native people, then disappeared. Some scientists have misused DNA samples taken from members of several indigenous nations, conducting studies the DNA donors didn’t consent to and doing studies that contradicted the groups’ cultural and religious beliefs.

In 2002, the Navajo (Diné) Nation — Tsosie’s tribe — declared a moratorium on genetic research. Recently, tribal members have discussed lifting the moratorium, but for now it remains in place, Tsosie says. “We’ve been, for so long, used as research subjects and not really equitable partners in research,” she says. “We’re still waiting for the conversation to change to allow us to have our interests protected.”

As a result of this mistrust of genetic research, there are not enough people from the 566 federally recognized tribes in the genetic databases to enable customers to learn about their tribal heritage from DNA tests. And even if a DNA test could establish that a person carries DNA inherited from a Native American ancestor, that doesn’t make that person a member of the tribe, Tsosie says. Tribal memberships are based on family and community ties, not DNA.

As a volunteer for the Native American Indian Association of Tennessee, Tsosie gets a lot of questions. People get Native American results and want to know if they can share in gaming profits. “It’s not enough to just call yourself a Native American,” she says. “I tell them, you have to go through the genealogy” and document your ancestry. “Typically, the response is, ‘Oh, that sounds like too much work.’ ”

That response baffles her. “If knowing this Native American past — this part of you — is so important, then undergoing the legwork and documentation should be important,” she says. Equally puzzling is why people base their identities on randomly inherited SNP patterns, she says. “Our character, who we are, who we come from is a complex story of a variety of nonbiological factors. To reduce that to a test kit is actually going to ignore the beauty and complexity that is us.”
Mix and unmatch
When genetic testing customers discover that they don’t share DNA with people they thought were their cousins, assumptions can get dark quickly. Are there secrets in the family tree? Not necessarily.

DNA recombination — a reshuffling of bits of the parents’ chromosomes in the cells that give rise to eggs and sperm — creates new genetic combinations, half of which each parent passes to a child. Siblings will share about 50 percent of their DNA. The recombination means children don’t inherit the exact same mix from their parents (unless the kids are identical twins).

That mixing may lead to distant cousins inheriting completely different genetic legacies from their ancestors. The more distant the connection, the more likely relatives are to have no DNA in common. About 10 percent of third cousins (who share the same great-great-grandparents) and 45 percent of fourth cousins (descendants of the same great-great-great-grandparents) have no DNA in common, says Drew Smith, a genealogical librarian at the University of South Florida in Tampa.

“Don’t get upset if you’ve got a documented third cousin and you don’t share any DNA. It happens,” he says. “On the other hand, if you’ve got a second cousin and you don’t share DNA, there’s a problem.”
Making connections
Some ads for testing companies reinforce the link between DNA and identity. An AncestryDNA ad features Kyle Merker, a real person, who says that he grew up thinking he was of German descent. He even danced in German folk groups and wore lederhosen. Merker’s DNA suggests he’s not German at all, but predominantly Scottish and Irish. He’s swapped his lederhosen for a kilt.

The commercial makes it sound like Merker changed his entire culture because of a DNA test. Dig deeper, though, and you’ll find that he researched his family through newspaper articles and government records. These traditional genealogical resources really told Merker the story of his family, Smith says.

“DNA by itself is rarely of any value,” Smith says. “If you’re really interested in researching your family, there’s much more work to be done.” He likens it to ads from Home Depot or Lowe’s: “They make it look like, ‘Oh my gosh, redoing a room is easy.’ ”

Similarly, to really confirm heritage, people have to follow paper trails composed of birth and death certificates, military forms, immigration records, census rolls, church baptism and marriage records, and more. “DNA is just one more type of record,” Smith says. “You’ve got to pull it all together to build your case.”

Michael Douglas found his Irish roots, but it took more than DNA to untangle his heritage. Douglas learned from a McCarthy lineage group on Family Tree DNA that his Y chromosome suggests he’s a descendent of Donal Gott McCarthy, a 13th century Irish king. “Oh, my god, I’m royalty!” he says. The group helped him trace the McCarthy lineage from the 1200s to 1830s Cork County, Ireland.
AncestryDNA’s and MyHeritage’s DNA and genealogical records allowed Douglas and four people he calls his “ancestry angels” to connect him with his biological family. The angels were four strangers who friended Douglas on Facebook and helped him with his family research, using genetic connections Douglas had rejected because they didn’t have the McCarthy last name. The helpers disappeared once he tracked down his mother.

Not all endings are happy. Smith has seen DNA testing split families. “You may discover things that are surprising or disturbing,” he says. You could find out that your father isn’t your father. Or matching to other relatives could uncover family secrets, such as an aunt who never told her family that she gave up a child for adoption or an uncle who knowingly or unknowingly fathered a child.

“It’s fun to learn more about our ancestors and what our ethnicity is,” Smith says. But, he warns, keep in mind that what you learn “may upend your personal life or the personal lives of members of your family.” Don’t do it if you’re not prepared for the repercussions.

Commercials abound for DNA testing services that will help you learn where your ancestors came from or connect you with relatives. I’ve been interested in my family history for a long time. I knew basically where our roots were: the British Isles, Germany and Hungary. But the ads tempted me to dive deeper.

Previous experience taught me that different genetic testing companies can yield different results (SN: 5/26/18, p. 28). And I knew that a company can match people only to relatives in its customer base, so if I wanted to find as many relatives as possible, I would need to use multiple companies. I sent my DNA to Living DNA, Family Tree DNA, 23andMe and AncestryDNA. I also bought the National Geographic Geno 2.0 app through the company Helix. Helix read, or sequenced, my DNA, then sent the data to National Geographic to analyze.
These companies analyze hundreds of thousands of natural DNA spelling variations called single nucleotide polymorphisms, or SNPs. To estimate ethnic makeup, a company compares your overall SNP pattern with those of people from around the world. SNP matches also help companies see who in their database you’re related to.

Some of the companies also analyze a person’s Y chromosome or mitochondrial DNA. Y chromosome DNA traces a man’s paternal line. In contrast, mitochondrial DNA traces maternal heritage, since people inherit mitochondria, which generate energy for cells, only from their mothers. Neither type of DNA changes that much over time, so those tests usually can’t tell you much about recent ancestors.

Once I sent in DNA samples, my Web-based results arrived in just a few weeks. But my user experience, and results, were quite different for each company.

National Geographic Geno 2.0
At $199.95, National Geographic’s test is the most expensive, yet the least useful. The results are generic, and the ethnicity categories are overly broad. My results say that 45 percent of my heritage came from people living in southwestern Europe 500 to 10,000 years ago. That doesn’t tell me much and doesn’t reflect what I know of my family history.
There’s no relative matching, though Geno 2.0 shows which historical “geniuses” may have shared your mitochondrial or Y chromosome DNA. I don’t know how National Geographic knows about the mitochondria of Petrarch, Copernicus or Abraham Lincoln. So I’m skeptical that I am actually related to those famous figures, even from the distance of 65,000 years, the last time we supposedly had an ancestor in common. The service also calculated the percentage of Neandertal ancestry that I carry. I take geeky pride that 1.5 percent of my DNA comes from Neandertals, topping the 1.3 percent average for Geno 2.0 customers.

Overall, Geno 2.0 has a nice presentation, but I learned more about my family history elsewhere. Since I bought the Geno 2.0 kit as an app through Helix, I don’t know if the kit purchased directly from National Geographic, which is processed by Family Tree DNA, would yield different results.

Living DNA
Another expensive test ($159) came from Living DNA. When I saw the company’s ad claiming to pinpoint exactly where in the British Isles a person’s genetic roots stem from, I decided to give it a go. The company highlights ethnicity on a world map, then lets you zoom in from the continent level. I found that 22.5 percent of my heritage came from Lincolnshire in east-central England. I haven’t yet traced any ancestors to Lincolnshire, but I did find through much genealogical sleuthing that one of my sixth-great-grandfathers came from Aberdeen, Scotland. Living DNA says that 3.1 percent of my DNA is from Aberdeenshire. Written narratives on the website provide a history of each reported region.
Using mitochondrial DNA and, if applicable, Y chromosome DNA, the company can trace your maternal and paternal lines back to human origins in Africa and show where and when your particular line probably branched off the original. My “motherline” probably arose in the Near East 19,000 to 26,000 years ago, Living DNA claims, and my ancestors were some of the first people to enter Europe. In February, the company announced that it would soon launch a relative-matching service for its customers.

I’m not sure the service would be worth the price tag for people whose ancestry doesn’t contain a strong British or Irish tilt, though Living DNA says it is working to improve ethnicity estimates in Germany and elsewhere.

Family Tree DNA
The most no-frills of the bunch is Family Tree DNA. For $79, “autosomal” testing looks for genetic variants on all of the chromosomes except the X and Y sex chromosomes. Y chromosome and mitochondrial DNA analysis costs extra.
Family Tree DNA allows a user to build a family tree, incorporating personal DNA tests and matches from the site’s relative-matching section. I found more than 2,400 potential relatives. A chromosome viewer lets me see exactly which bit of DNA I have in common with any particular relative, or with up to five relatives at a time. That feature also allows users to trace how they inherited DNA from a shared ancestor. But I found this tool difficult to use.

The website offers little explanation of results. For instance, I was excited to see that my DNA was compared with that of ancient Europeans, including Ötzi the Iceman, who lived 5,300 years ago (SN: 9/17/16, p. 9). Family Tree DNA is the only company I tried that incorporates ancient DNA into its results and that feature was what convinced me try this company. I did get a breakdown of how different groups — Stone Age hunter-gatherers, early farmers and “Metal Age Invaders” from the Eurasian steppes — contributed to my DNA. But when I saw Ötzi’s dot on my ancestry map, it wasn’t clear if that meant we share DNA or if the map was merely showing where he lived.

23andMe
23andMe ($99) offers one of the more complete packages of information. Most companies show a map of ethnic heritage. 23andMe does, too, but also presents an interactive diagram of all of a person’s chromosomes, indicating which portions carry a particular ethnic ancestry. Because my parents also did 23andMe, I learned that my dad handed me a tiny bit of chromosome 15 that carries western Asian and northern African heritage. My mom gave me the 0.3 percent of my DNA that comes from the Balkans, in a single chunk on chromosome 7, which makes sense since her grandparents came from Hungary. Playing with the chromosomes is fun. But I question the accuracy of these results (see my related article for more on why ancestry tests may miss the mark).
23andMe presents Neandertal heritage in terms of the number of genetic variants you carry. A family-and-friends scoreboard shows where you stack up. (I top my leaderboard with 296 Neandertal variants, more than what 80 percent of 23andMe customers have.) The report also explains what some of those Neandertal variants do, including ones linked to back hair, straight hair, height and whether you’re likely to sneeze after eating dark chocolate. The company doesn’t test for all possible Neandertal variants, including ones that have been linked to health (SN Online: 10/10/17; SN: 3/5/16, p. 18).

Like Geno 2.0, 23andMe uses mitochondrial and Y chromosome DNA to trace the migration patterns of a person’s ancestors, from Africa to the present day.

Relative matching is both interesting and frustrating. I could see the people I match, how we might be related and compare our chromosomes. But 23andMe doesn’t provide a way to build family trees to further explore these relationships.

AncestryDNA
AncestryDNA ($99) doesn’t give the variety of information other companies do. But it has useful genealogical tools, provided you link your results to a family tree that you can build with help from historical records via a paid subscription to Ancestry.com.
One interesting feature of my heritage report was that it went beyond spots on the map in Europe to also show a region of the United States called “Northeastern States Settlers.” A match to that category tells me that my ancestors who came from Europe probably initially settled in New England or around the Great Lakes. They did. One branch of my family tree set roots in Massachusetts in the 1640s. Using birth, death and immigrant records from Ancestry.com, I could build a timeline to show when and from where individual ancestors immigrated to the United States.

AncestryDNA also matches you with relatives, but you can only see how you’re related to those people if they have also chosen to make family trees.

A feature unique to AncestryDNA is called DNA circles. It shows connections between individuals and family groups who share DNA with you. These circles also contain descendants of your ancestors who you don’t directly share DNA with. Therefore, this feature allows you to extend relative matches beyond what traditional DNA matching can do.

For instance, I am in a family group with my uncle and a cousin. We all share DNA with 24 other descendants of Samuel Pickerill, a drummer during the Revolutionary War. Pickerill has 42 other descendants with whom my family group doesn’t share DNA. Those 42 Pickerill descendants happened to inherit different bits of DNA from Pickerill than my uncle, his cousin and I did. That sometimes happens because of the random nature of the rules of biology and genetics (for more on those rules, check out this video).

Genealogy junkie
Although I’ve always been interested in family history, DNA testing has gotten me hooked on genealogy research.

23andMe and AncestryDNA were the most fun to use. 23andMe can tell me whether a relative is on my mother’s or father’s side of the family. But then I have to go back to AncestryDNA and comb through my family tree to learn how we’re really connected. DNA can kick-start a genealogy hunt, but combing through marriage certificates, military rolls, census records, immigration documents, old photographs and other records — which Ancestry.com can provide — is what really tells me who my ancestors were.