I hope this helps to clear things up. Ancestry DNA testing is not an exact science, and is limited by the fact that we don't inherit the exact same DNA our parents had, meaning that with each new generation, old DNA is lost. Ancestry tests can provide estimations of our genetic ancestry, and though they are improving all the time, they can't tell the whole story of our heritage.
Once your genetic information is out there, it’s difficult to undo. Also, once you know something about yourself, it’s impossible to forget. Revelations such as having different parents than you expected or finding unknown half-siblings are difficult to process at any age, but it’s particularly troubling for kids. However, you can always simply opt out of family matching features.

Your DNA information is gathered using saliva capture, which, once analyzed, is stored forever on 23andMe's servers. The service also provides for a chromosome browser and comparison, as long as any possible matches approve your access. The service's matrilineal and patrilineal line testing can geolocate your DNA ancestry in more than 1,000 regions. 


One of the most popular reasons for doing a DNA test is to determine ethnicity.  Many people start out on their DNA journey trying to learn about their ethnicity and end up discovering new family members, or learning something really cool about their family history.  Is there such a thing as a DNA test for ethnicity, and if so, which one is the best?

Companies differ in terms of which reference populations they use. Some companies will create their own reference populations, while others will use populations identified in published studies. For example, 23andMe produce their own reference populations by sampling their customers (as long as the grandparents of those customers were all born in the same country). They then combine this data with public population data, produced by projects such as the Human Genome Diversity Project.
When a sample of biological material contains DNA from more than one person, this can result in a “mixed DNA profile”. In such profiles, there may be a reduced amount of useful information regarding whether or not a specific person could have contributed to this sample. This could be because the contributors may share one or more DNA alleles, resulting in the masking of the DNA of one person by that of the other.
If you're creeped out by how much information Facebook, Google and Amazon have on you based on your online browsing habits, just remember that these DNA testing services are getting what is effectively your medical history. Make sure of their policies before turning over that valuable data. Also, even if you don't share your DNA with a service, your familial DNA data may be available if a relative shared their genetic material. The privacy issues can get very complex.
23andMe started out by testing for genetic markers of diseases and medical conditions before rolling that back in response to the governmental concerns. It has since started slowly adding more health-related features with approval from the FDA. In April, 23andMe got approval to offer risk analysis for ten genetically linked diseases. The company now offers two options: Health + Ancestry ($199) and Ancestry ($99). The Health + Ancestry plan includes testing for genetic health risks and carrier status, as well as reports on your genetic weight, hair loss, and other traits.
Some concerns about the ultimate efficacy of certain home tests seem to emanate from the industry itself. I did a telomere-measuring test (a mouth swab) by Titanovo, based in north Colorado, which came back saying that my telomeres were too short, putting me at 10 biological years older than I am. However, when I contacted Titanovo, it explained that it had stopped telomere measuring and was now concentrating exclusively on its DNA-utilising “bioinformatics” health, fitness and wellbeing website (analysing client data from other genetic testing sites).
The 23rd pair of chromosomes is comprised of sex chromosomes – X and Y chromosomes that determine whether you’re male (XY) or female (XX). Traits like red-green color blindness, male pattern baldness and hemophilia are specifically linked to X or Y chromosomes and are called sex-linked characteristics. All of those examples, and most other sex-linked traits, are X-linked and more common in males, who only have one X chromosome. Many DNA tests isolate Y DNA in males to show consumers their paternal haplogroup. Since the Y chromosome is directly inherited from father to son, it is possible to trace direct paternal lineage for many generations.
The technique of DNA profiling was developed by Alec Jefferys in the mid-1980s and is based on the analysis of markers in DNA known as microsatellites or Short Tandem Repeats (STRs). These markers are found at specific points (also called loci) in everyone’s DNA and they’re motifs of two-six bases (the units that make up our genes) that are repeated numerous times. The exact number of times these markers are repeated differs between individuals, but members of a family will share the same or a similar number of repeated markers, depending on how closely related they are.
The DNA test thing is a scam as the results cannot have precision. I know where my recent ancestors came from and wanted to “test a DNA test”. My ancestry is 3/4 Spanish Valencian and 1/4 Spanish Ibizean (Ibiza): I have family papers and village names for my recent ancestors: they all have typical Spanish/Catalan names and I expected this to be reflected in my results.
When you get your 23andMe results, it takes you to an easy-to-navigate dashboard with your ancestry composition report front and center. Testers reported both high levels of confidence in the accuracy and high rates of satisfaction with the contents and detail of their results. The service breaks down the world into 171 populations, based off its reference panel of 10,000 individuals with known ancestry. Some of these population groups are a tad redundant. For example, I received hits for South Korean, Korean, Broadly Japanese & Korean, and Broadly East Asian in my report, which all represent a similar area but show different levels of certainty. Scrolling down your ancestry summary, you can also view your ancestry timeline. This estimates how many generations back your most recent ancestor from each of your matched regions probably lived. You can also view your ancestry composition mapped out on chromosomes. This view is interesting, as you can change the level of confidence from speculative to conservative, which equates a match percentage of 50 to 90 percent.

The 100,000 Genomes Project is an NHS initiative, run by Genomics England, and is the largest national genome sequencing project in the world. On entering, patients have their entire genome, of more than 3bn base pairs, sequenced. This is different from commercially available genetic testing kits, such as those from 23andMe, which only look at very small stretches of DNA in a process called genotyping. The hope of the NHS is that having so much genetic information, from so many different people, will allow “groundbreaking discoveries about how diseases work, who could be susceptible to them, how we can treat them, and what treatments might work”.


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As well as showing you which ethnic groups you’ve inherited your DNA from, autosomal DNA tests can also be used to find living relatives and build your family tree. Many people attempting to build their family tree will often make breakthroughs in their research when they combine a DNA genealogy test (such as an ethnicity test) with traditional genealogical techniques.

Companies differ in terms of which reference populations they use. Some companies will create their own reference populations, while others will use populations identified in published studies. For example, 23andMe produce their own reference populations by sampling their customers (as long as the grandparents of those customers were all born in the same country). They then combine this data with public population data, produced by projects such as the Human Genome Diversity Project.

Who knows how much of it made solid scientific sense? However, I have to confess that I rather enjoyed it on the level of an indulgent genome-oriented “pampering session”, just as I had a hoot with the ancestry/Neanderthal/earlobe data on 23andMe. Where Thriva is concerned, I also noted that it did advanced thyroid tests. Although such tests are available from the NHS, I’m hypothyroid myself and I know that sometimes it can be difficult and time-consuming getting tests repeated and it could be useful to be privately tested in this way.

Even though we are all unique, most of our DNA is actually identical to other people’s DNA. However, specific regions vary highly between people. These regions are called polymorphic. Differences in these variable regions between people are known as polymorphisms. Each of us inherits a unique combination of polymorphisms from our parents. DNA polymorphisms can be analysed to give a DNA profile.
Therefore, when the markers in two samples are analysed, the number of times that they’re repeated can be compared and the statistical likelihood that they came from the same person or from two closely related individuals can be calculated. This is why DNA profiling can be used to establish biological relationships, as well as to connect DNA evidence with a criminal suspect.
So what are you waiting for? If your family’s genetic signature hasn’t yet been tested, how about considering contributing to the genealogical record and resource for your family by finding one or two men to take a Y-DNA test. If you are a male S-NN-T descendant then please check out the Sinnott/Sennett (and variants) surname project at familytreeDNA.com – you even get a discounted rate for the Y-DNA37 test if ordered through the project. http://www.familytreedna.com/group-join.aspx?Group=Sennett
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