Every company providing DNA testing has their own database of DNA samples. These are called AIM’s or ancestry informative markers. These markers were derived from the current populations of America, Asia, Europe and Africa. Every database is looking for a pair of genes located on a specific chromosome in a specific position. The way the DNA is evaluated is through the SNP’s or the single nucleotide polymorphisms. The SNP’s are chosen according to the frequency in a specific geographical population. Your SNP’s are compared to the most common SNP’s for the various populations in the company’s reference database. The results are not conclusive because they are based on common genetic variations. The probability for your DNA being from a certain country is based on a comparison between your DNA and the database. If you used a different company, they would have a different database. This means your results would most likely differ. According to studies, the lowest concordance is with individuals of South Asian, East Asian and Hispanic descent.
You might want to stay away from DNA tests if you or any of your close relatives have committed a crime. Although ancestry DNA testing companies don’t typically share database information with law enforcement, consumer DNA tests may result in future identification. For example, FamilyTreeDNA, which has a database of close to a million samples, has agreed to give the FBI limited access to the company's DNA database. This access consists mainly of consumer-level insights, like matches with other members of the FamilyTreeDNA community who have enabled family matching; by law, however, more in-depth investigation requires a subpoena.
The National Geographic database doesn’t specialize in finding long lost relatives, but the Geno 2.0 test does give you plenty of information linking you and your DNA to the past. With autosomal, mitochondrial and Y-DNA genotyping, the Geno 2.0 test examines your ancestry in three time periods, including your Regional Ancestry report, which spans 500 to 10,000 years ago. The test also delves into your Deep Ancestry through your maternal and paternal line haplogroups and you Hominin Ancestry, which tells you how much Neanderthal DNA is hanging out in your genetic code. One quirky but interesting feature explores possible relations to famous geniuses throughout history and estimates how many thousands of years ago you shared a common ancestor with Abraham Lincoln or Charles Darwin. Testers appreciated the amount of information and context given with each report. For example, the regional ancestry report matches your DNA to broad world regions on a map, but it also compares your DNA to two more-specific reference populations. My regions were Northeastern Asia and South China Sea, which fit the Korean and Japanese reference populations. Another tester was matched to 11 geographic regions throughout Europe, North America and West Asia, and they were matched to Argentinian and Puerto Rican reference populations. The Geno 2.0 test uses a Helix spit-tube test, which is extremely easy to register. It took National Geographic 27 days to notify testers of results. Because Helix uses exome sequencing instead of the more-common genotyping, you cannot download your raw DNA information from this test to upload into other databases. You can, however, purchase more DNA apps from the Helix Marketplace to run your data through partner databases without submitting additional samples.
Most direct-to-consumer DNA test companies warn that the tests may reveal things you wish you didn’t know about your family. For example, you could find out that one of the people who raised you isn’t your biological parent or that there’s an entire branch of your family you didn’t know about. There isn’t a way to prepare for a shock like that, but you can opt out of a company’s family-matching services if you’d rather not know.
Thank you for such detailed information. I’m considering buying a DNA ancestry kit for my wife for Christmas (and buying one for myself as well). After reading your article (and many of the wonderful comments), I’m leaning towards the one from Ancestry.com. However, would I still get complete results without a subscription? I looked on their website and it doesn’t say.
In Newman’s view, the genie is out of the bottle with home genetic-testing kits. He says that while the kits could potentially provide data in the future, right now, they lack “clinical utility” – they look at genetic variants that, individually, have a very low chance of predicting specific health risks, as there are too many variables: “It’s like the Opportunity Knocks clap-o-meter, with some people further along the scale, and therefore more likely to get the condition and then people at the other end of the scale, who are unlikely to get it.”
Next, you'll receive an email alert that your results are ready, and that's when the fun begins. Your results may not be as dramatic as those portrayed in TV ads, but you may find some surprises. One important note: Results are different for women and men. Women, who have the XX chromosome, can only trace back the maternal line. Men, having the XY chromosome, can track back the maternal and paternal line, painting a complete picture. If you're a woman, it's worth asking your brother, if you have one, to take a test and share the results. When some of these services ask for your sex when you order your kit, they simply want to know about your chromosomes.
In this case, I would recommend two options: 1. Ancestry.com – If you choose to take their DNA test, you can also take advantage of their family tree feature. Your DNA test results would be compared to other samples in the database. Combining this, with a manual lookup you can do, you might trace relatives on your father’s lineage. 2.LivingDNA – LivingDNA provides a separate unique analysis of the paternal lineage. This analysis will give you an in-depth picture of your father’s heritage. The only drawback is that LivingDNA database is relatively small (compared to ancestery.com and other big competitors). You can bridge that gap using GEDMatch service, by uploading your raw DNA data (acquired by LivingDNA). You can read more about GEDMatch here. Good luck and I hope you would find what you are looking for!

Bill Newman, professor of translational genomic medicine in the Manchester centre for genomic medicine at the University of Manchester, and chair of the British Society of Genetic Medicine, says that such tests in this context simply don’t make sense and that, usually, telomere testing would only be used in in-depth studies of ageing and diseases associated with ageing. “There’s some really brilliant work going on, by some of the best biologists in the world,” says Newman, citing Elizabeth Blackburn, who won the 2009 Nobel prize for medicine for her work on telomeres. “But there’s no evidence whatsoever that measuring a person’s telomeres gives any indication about their health – or beauty, intelligence, or anything else that might be listed on these sites.”
Gteat article! Thank you so much. I am Jewish American. Both sides of my family immigrated from Eastern Europe/Russia about 5 generations ago. I would really like to try and find out more about exactly where they came from, identify potential living and deceased distant relatives in the USA and abroad and ultimately start creating an extensive family tree. Which test would you suggest?
“My concern is that more and more of these tests are being put out, and people are being persuaded to have these tests done, and they get results back that are very often of very low value and dubious helpfulness,” she says. “And often people are told to go to see their GP and that then places a direct stress on the NHS, at no cost to the company. The companies make their profits and walk away, letting the NHS sort out all the fallout, the push-back, from the test results, in a way I find absurd. Why should the NHS have to prop up the problems that these companies create?”