Most of the services we tested use genotyping to read your DNA. Genotyping looks for specific markers in your genetic code. For something like ancestry testing, genotyping is effective because it identifies known variants in your DNA. Scientifically speaking, genotyping’s weakness is that it can only recognize previously identified markers. This is one reason DNA tests’ accuracy relies so heavily on the DNA database size; there must be enough information available and identified genetic variants in the database to recognize new customers’ markers.


As discussed earlier, in order to determine the ethnicities present in your genetic make-up, genetic ancestry companies can analyse your autosomal DNA to seek out the genetic variants uniquely associated to certain population groups. These groups are known as ‘reference populations’, and they’ve been constructed by sampling the DNA of modern populations around the world, as well as from human remains at various archaeological sites. By identifying these genetic variants in your genetic code, companies can report on the groups that have contributed to your DNA.
Some DNA analysis uses the Low Copy Number(LCN) method. This is a modification of the more commonly used SGM Plus method of analysis. The advantage of LCN analysis over standard SGM Plus is its extreme sensitivity; however this is also a disadvantage. The effects of cross contamination are more prevalent in LCN analysis, and due to various effects observed when amplifying very small amounts of DNA any LCN profile should be interpreted with caution.
In order to truly understand what a DNA estimate is, we have to get a little bit scientific.  The DNA testing companies use something called “sample populations” in order to give you your ethnicity estimate.  Their laboratories compare your DNA with that of thousands of people from all over the world.  In order to become a part of the same population, the participants would have needed to prove that they and their ancestors have lived in the same geographic area for several generations.  Their DNA is then grouped by geographic area.
I was born in NYC, the youngest of five kids. My parents and three older siblings were born in Bogota, Colombia. My name implies Hispanico/Latino roots but when I’m with my Polynesian friends people always think I’m Hawaiian or a mix of Polynesian and something else. I recently attended a Nepali church service and people asked me what part of Nepal I was from.
The results came out as half French, 40 % Spanish, some Italian, 1% Sardinian, 1% scottish-Irish. The major problem is that ancient Ibiza DNA has evolved to resemble that of modern French, same thing for Spanish-Valencian DNA: which is shared by modern French people. So if you do have French ancestry, it may show as Spanish and vice versa… THIS GOES FOR EVERYTHING ELSE: IT’S WILL BE VAGUE!
Otherwise, the home-testing kits could be said to fit in with our increasingly health-conscious and, if you wish to be cynical, narcissistic times. What says you’re “special” more than finding out everything about yourself, right down to the nitty-gritty of genetics? In this way, these kits could be viewed as the latest plaything of the “worried well”. You could see how the scientific approach would appeal to the health-obsessed of all sexes and ages, your marathon runners and serious gym-goers, who take their fitness extremely seriously.
The spit is for one of the home genetic-testing kits I’m sampling. A growing number of these kits (brands such as 23andMe, DNAFit, Thriva, MyHeritage DNA, and Orig3n) promise to unlock the mystery of your genomes, variously explaining everything from ancestry, residual Neanderthal variants, “bioinformatics” for fitness, weight loss and skincare, to more random genetic predispositions, denoting, say, the dimensions of your earlobes or the consistency of your earwax.
GEDmatch is a service where anyone with raw DNA data can upload it, see a list of cousin matches and use a powerful selection of advanced tools to analyze their data. The service is free and powered by donations (extra tools are provided to those that donate). From parental phasing and triangulation, to a variety of admixture calculators and a robust database of people from all testing companies, GEDmatch is the best place to go to explore your genetic data in detail. The system accepts raw data from any one of the main testing companies and has a proven track record of properly managing user information.
Finding small percentages of unexpected ethnicities may prove to be inaccurate upon further examination, and NOT finding traces of a certain group, such as Native American, may not necessarily prove that you do not have ancestors from that region or group. You can read more about that as it pertains to Native American research here. You can apply this statement to any ethnicity or region you might expect or hope to find in your results.
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Looking at your raw DNA file might not give you any useful information unless you’re looking for a specific marker. You can also upload the file into a third-party DNA databases for information or results beyond what’s available from your testing company. This process is not without risks, as your DNA testing company only ensures the security of your personal information in its own environment. Once you download the file, you’re responsible for the file’s security. However, uploading your raw DNA to a third party database isn’t inherently unsafe — just be cautious.
AncestryDNA has the largest database to compare your results to when making matches, with 23andMe coming in second and FTDNA in fourth. MyHeritage DNA, although newer than the others, is catching up fast and numbers now surpass FTDNA. Current numbers can be seen in the chart above and are estimates based on available data. Each of these databases is growing, some of them quite rapidly.
Written out the base pairs in DNA make a sequence, e.g. A T A T C G C G T A A T G C. More than 99.9% of those bases are the same in all people. The order, or sequence, of the letters determines the information available for building and maintaining an organism, similar to the way in which letters of the alphabet appear in a certain order to form words and sentences.
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