The trick for collecting a saliva sample is to give yourself plenty of time to create enough spit to fill your tube to the fill line (not including any bubbles). You should not eat or drink anything for at least an hour before collecting your sample, so it’s best to plan to collect your sample before eating. Our testers collected samples before lunch and found that thinking about the upcoming meal made saliva production easier, particularly as we collected multiple samples. Planning ahead and making sure you stay hydrated before you collect a saliva sample helps as well.
23andMe is a bit different in that many people have tested with their company for the health results and are not necessarily interested in genealogy or matching with relatives, even if they opted into this feature. That doesn’t mean you won’t get a good response when reaching out, but it may be less common than with the other testing companies. Recently 23andMe has been placing more focus on genealogical testing, however, so this is may be shifting.
So, back to the example of the two men (lets call them John and James) we think might be brothers: We find two g-g-grandsons (or any male descendant in a direct father-son line) of each, preferably the most distant cousins we can find, and get a Y-DNA test done for all four men. Usually a 37 marker Y-DNA test is a good place to start. This looks at 37 sections of each persons DNA that the genetic scientists think are most useful for our purposes (the bits that are least likely to randomly change over generations). The results come back looking like a fairly meaningless string of numbers which are fairly useless on their own, but allow us to compare each persons result with others in the database of the testing company.
Newman says that there’s a basic lack of “literacy” and understanding about genetic testing, among the public and even other health professionals. People are given false reassurances or made to panic (just because you have certain genetic variants, it doesn’t mean that you will develop a particular condition). Newman also makes the point that, in his field, counselling happens before and after testing and, while people with cancer or heart issues nearly always opt to have the test (as they can then take action to varying degrees), often people with conditions such as Huntington’s disease in their family decide not to go ahead because a diagnosis would change nothing for them. In any event, Newman says that, with genetic testing, while there are different levels, intensive counselling is always “absolutely key”.
In fairness to 23andME, it leaves it up to the customer to unlock the more serious results – or not. When I unlock mine, I discover that, while I’m not genetically predisposed to such things as the BRAC1 or BRAC2 variant, Parkinson’s or MS, I have one of the variants for late-onset (mid-80s) Alzheimer’s. However, I don’t have any other markers for Alzheimer’s or family history or conditions associated with it or anything else listed in the rather lengthy disclaimer, which also stresses that it’s not a diagnostic result and to seek further advice from your GP if you are concerned.
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 SGM Plus system of DNA analysis targets ten loci, each of which contains two alleles. These are the “short tandem repeats” that vary between individuals. In addition, a further locus is targeted that acts as in indicator of the sex of the donor. A “full” DNA profile is one in which all of these loci have produced a reliable and reportable result. Occasionally, the processes used to target some of these loci fail, resulting in an incomplete or “partial” DNA profile. The most common reasons for such failure are either that a very small amount of DNA was present in the sample, the DNA may have become degraded, or that substances may have been present in the sample that may have inhibited the analysis process. Depending on the degree of success of the DNA analysis, the match probability calculated from a partial DNA profile may be reduced below the 1 in 1 billion that would be obtained from a full profile.
A few of the DNA tests we tested, including the National Geographic Geno 2.0, use genetic sequencing instead of genotyping. Sequencing is newer in the mainstream direct-to-consumer DNA testing market, as it used to cost more and take much longer to sequence a person’s DNA. Sequencing identifies the exact makeup of a certain piece of DNA – be it a short segment or the whole genome. The Helix tests sequence the Exome, which are the parts of the genome responsible for protein production, plus several other regions of interest. 
Whole genome sequencing is the most accurate representation of your DNA that you can buy, as it provides you with the details of every single base in your DNA (more than 5 billion). This is unsurprisingly much more expensive than DNA profiling, and isn’t necessary if you are looking for a profile for identification purposes. However, if you’d like to know more about DNA sequencing, we’ve listed the companies that can sell you your sequence.
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.
The little changes are where “mutations” occur over generations – these aren’t necessarily bad, it just means that the gene has been copied slightly differently as it passed from father to son. Because its possible to predict how often mutations are likely to occur, comparing the Y-DNA from distant male cousins with a common ancestor (and seeing how many differences there are in a standardised set of markers tested) allows a rough estimate of when that common ancestor might have lived. A very close match between two men who share a common surname (only one or two differences) makes it very likely they are related, and a bigger number of differences makes it either less likely they are related, or that the most recent common ancestor is very many generations back.
TTR-related hereditary amyloidosis typically develops in adulthood, but age of onset can vary widely. People with the V122I variant typically develop symptoms after the age of 60. People with the V30M variant can develop symptoms as early as their 20s or as late as their 90s, depending on ethnicity and family history. People with the T60A variant typically develop symptoms between 45 and 80 years of age.
FTDNA has the most advanced tools for easily analyzing cousin matches as of now, although it is possible that MyHeritage DNA may catch up. They seem very eager to please customers at this point. FTDNA does fall short when it comes to the ability to sync with developed family trees however. This is certainly not intentional on their part, they have developed some great tools for this purpose, but FTDNA (unlike Ancestry and MyHeritage) does not provide record searches or an online family tree program for the purpose of genealogical research. For this reason they are inherently limited in this regard.
It’s worth bearing in mind that when you’re presented with the population groups that have contributed to your DNA, some of the groups revealed may be very general (e.g. Western European) and the report may not tell you when or for how long each group was located in the region that it’s named after. The specificity of the population groups depends on the reference populations used by the company you test with (discussed later). Therefore, if a detailed ethnic breakdown is important to you, look for example reports from the company you’re considering, or get in touch with them to ask for a list of the reference populations that they use.
As stated at the start of this guide, each one of the main tests will provide you with easy-to-use reports and cousin matching that you can use in your genealogy research. You will need to carefully review the information provided in this guide to make a decision about which test is best for your particular needs. You may also choose to test with (or upload your results to) multiple companies.
DNA test companies that use genotyping technology, including 23andMe and Ancestry, allow you to download your raw DNA file. A raw DNA file is usually a text file that contains all the information about your genetic code gleaned from the company’s examination of your DNA. This is comprised of several hundred thousand markers known as SNPs (Single Nucleotide Polymorphisms). Most raw files are organized into five columns: the SNP coded into an rsID number, the chromosome the SNP is located on, the location of the SNP on the chromosome and the two alleles for each SNP.
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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.
And that’s where it starts getting interesting, because then we can start comparing that genetic signature to the results from other men who share the same surname but don’t appear on our family tree. If the matches are close, then we can start thinking “is there a common ancestor for these families another generation or two back? Are the families linked in some way?”. Depending on what we already know about either family group, it can help target the paper research to get those families linked, or take us back another generation or two.
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