20 Secrets You Need to Know about Genealogy Tests

Whether it's because you caught an episode of Finding Your Roots on PBS or your friend found out through a mail-in DNA test that they were half Tazmanian, you've probably considered taking a genealogy test. These tests, which inform you of your genetic heritage, can be a fascinating journey of self-discovery or a fun conversation piece for a cocktail party. Either way, there is more going on below the surface of these DNA tests than you ever knew. Read on to discover what they are. And for more on the powers of your genes learn how our correspondent used DNA Testing to Lose Weight—and how the experience changed her life.

Though the genealogy testing services like to present themselves as straightforward and rooted in clear-cut science, the truth is that they have a track record of falling short. Case in point: Inside Edition investigated had a set of triplets send their DNA to both 23andMe and AncestryDNA. Neither of the services returned even close to identical results for the identical siblings.

While it's fun to learn about your ancestors and ethnic background, these tests can also detect important health information and identify if you are at risk of certain genetic diseases, such as Alzheimer's or breast cancer. But proceed with caution. While you may learn that you're genetically predisposed to having a single nucleotide polymorphism—or SNP (pronounced "snip" in the DNA testing world), which is a variation in an individual's DNA compared to the usual base in that position—it may be such a rare disease that the chance of you actually contracting it are still very low. Best to consult a health professional before panicking. And for more great health knowledge, check out the 20 Surprising Habits That Increase Your Cancer Risk.

In March 2018, the FDA gave permission to 23andMe to provide customers with information about their cancer risk—specifically, whether they had certain mutations in the genes BRCA1 and BRCA2, which significantly increase the risk one has for breast or ovarian cancer. This marked the first direct-to-consumer genetic test of cancer risk.ae0fcc31ae342fd3a1346ebb1f342fcb

While identical twins or triplets should have identical results, that is not true of all siblings, even though you are produced by the same parents. As AncestryDNA explains, "The DNA we inherit from each parent is completely random, so unless you're an identical twin, your DNA profile won't be exactly the same as a sibling's." For more knowledge about your own physiology, check out these 50 Secret Messages Your Body Is Trying to Tell You. 

Genealogy testing companies search your DNA for the specific variations that vary from one person to another (as opposed to the vast majority of our genome sequence, which is shared among all humans), known as single nucleotide polymorphisms, or SNPs.

DNA tests can run the gamut as far as the number of markers tested. Some look at 12, or 37, or even 67 markers and can get very different results between them.

Obviously there wasn't genetic testing going on centuries ago, so services like AncestryDNA are actually comparing your results to those of other people who have taken the test, and looking for ancestors you might share on their online family trees.

While these kits make for fun gifts or serve as casual entertainment, some medically focused kits require a prescription and are really expensive. For example, Fertilome, which can show whether a person has a higher risk of fertility problems (in order to help them decide whether to freeze their eggs), costs $950.

According to AncestryDNA, two out of three people who have taken its test have found they are at least 5 percent Irish. It offers the example of a group of coworkers who had a contest to see who was the "most Irish." It turned out the winner grew up in Australia.

Some genetic testing companies will connect those submitting their DNA data with genetic researchers who will pay to be able to use their information in studies. For example, Genos can connect users with researchers willing to pay $50 to $250 for data used in their research.

The recent arrest of the man suspected of being the Golden State Killer was done by analyzing the DNA found on the scene of the murders and creating a fake profile on the genealogy site GEDMatch. It eventually connected investigators to the killer's relatives and the suspected killer, 72-year-old Joseph James DeAngelo.

Critics worry that using DNA data in this way could be dangerous for individuals' privacy—and the privacy of their relatives. As one user wrote, "My relatives consented for their data to be used for genealogy but not for criminal investigations."

Whether due to pride in believing they are of a certain ethnic background when it turns out they are not—or racism that makes it hard for them to accept they have a genetic background they would rather not have—some who apply for genetic testing don't like their results.

As one researcher revealed, "I've had boyfriends wanting to impress girlfriends, somebody who wanted to get into the Knights of Columbus, and I even had someone trying to prove he was part Native American to join a tribe. We won't change for fraudulent reasons, and besides, even if we did, these tests only give an indication."

DNA tests have been responsible in a number of cases of reunited long-lost siblings. For example, a pair of sisters who had been separated for more than 50 years were reunited after being connected through a 23andMe test. In another case, a man connected with his half-sister, whom he'd never met, using AncestryDNA. And for more feel-good family news, see the 15 Ways Your Siblings Shape Who You Are.

Tests called "cell-free fetal DNA testing," offered by a number of pharmaceutical companies, allow for expecting moms to test the DNA of their fetuses simply by drawing their own own blood. As Wired explains, "They presage a future when we can easily scan for a range of genetic defects, from the truly devastating to the not-so-serious, allowing parents and doctors to look past a baby's organs, beyond its cells, and down into its very DNA."

A service called Embark has been called "23andMe for Mutts" and allows owners to figure out the breed, genetic ancestry, and potential health risks their pet dog might face. The service came in handy recently in reuniting a dog that had been displaced due to Hurricane Harvey with his same-litter sibling. And for more dog news, see the 25 Photos Proving Dogs Are the Best Co-Workers.

Genealogy tests have been the central focus of no fewer than three major U.S. shows over the past few years, from the celebrity-filled Who Do You Think You Are, the Henry Louis Gates Jr.-hosted (and also celebrity-filled) Finding Your Roots, and the more populist Genealogy Roadshow.

Since the tests draw on data from others who have submitted their DNA samples, many of these services tend to overrepresent those from those with European backgrounds (where they have been historically more popular) and have less to draw on when it comes to populations with roots in the Middle East or Asia. Of course, as more people supply their information, more gaps will be filled.

Sending off a cheek swab seems innocent enough, but some people have raised concerns about what exactly DNA companies are doing with your most personal of data. Last fall, New York Senator Chuck Schumer called for more scrutiny of the services, saying, "Here's what many consumers don't realize, that their sensitive information can end up in the hands of unknown third-party companies… There are no prohibitions, and many companies say that they can still sell your information to other companies."

Identical twins have tracked down each other thanks to DNA tests. Last year, one woman whose parents adopted her from a South Korean orphanage tracked down her identical twin through 23andMe.

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