When asked about how database size affects ancestry results, David Nicholson, co-founder of Living DNA, told us, “The tests absolutely rely on the reference database. If you have Polish ancestry but there are no people in the database who are Polish, then what the test will do is show what the next closest group is next to Polish, like German or Eastern European ancestry.” 
There are many places you can upload your raw DNA, and several of them are free. Popular third-party DNA analysis tools include GEDmatch and Promethese. GEDmatch is a free, open database and genealogy site that gives additional DNA relative matching and trait results. This tool has information from users of multiple different testing companies. Promethease compares your raw DNA information against scientific reports that link certain markers to health conditions, though you should take these results with a grain of salt as genetic links do not equal a diagnosis.
DNA profiling isn’t exclusive to human DNA. Animals also have genetic markers in their DNA which can be used to build up a profile for DNA identification or determining parentage. The most common animals that this is used for are dogs. Similarly to human DNA profiling, dog DNA profiling uses 10-20 markers in order to build up a profile that can be used to identify your dog if it is ever lost or there is some kind of ownership dispute. Companies that offer this service will often include the profile in the form of a certificate, with details about your dog along with its DNA profile. It should also be said that these companies tend to store your dog’s profile in their database, so you that you can check back with them if you ever need to.
More controversially, some of these kits profess to tell you your biological (as opposed to actual age) by measuring the length of your telomeres (in basic terms, the caps at the end of each strand of DNA that protect chromosomes, like plastic tips at the end of shoelaces). Other tests, such as 23andMe, predict higher risks of developing serious conditions, such as multiple sclerosis, Alzheimer’s and Parkinson’s, including the test for BRCA1/BRCA2 (breast and ovarian cancer) that Angelina Jolie famously underwent, going on to have a preventative double mastectomy and surgery to remove her ovaries.
We similarly advise caution for the multitude of non-diet health and wellness DNA tests, which offer insights into your sleep, food sensitivities, and vitamin and mineral levels. And double that for medical information found in consumer DNA kit test results. While medical insights learned from taking an at-home DNA test may be interesting, it’s best not to take them too seriously. If you have a concern about a genetic predisposition to a disease, it’s best to talk to your doctor instead of relying on a direct-to-consumer kit. 

FTDNA is the market leader for both Y-DNA and mtDNA testing, and has the world’s largest Y-DNA and mtDNA genealogical matching databases. They are the only company that allows complete integration of Y-DNA, mtDNA and autosomal DNA test results for genealogical purposes. They host a wide variety of surname projects, haplogroup projects (Y-DNA and mtDNA), and geographical projects. Experienced and knowledgeable volunteer project administrators can often provide advice and help with the interpretation of results. They are not the first choice for autosomal DNA because of the smaller database but matches are more likely to be responsive and interested in genealogy.
As a postscript, I eventually end up having an interesting chat with Titanovo about my “bioinformatics” (distilled from my 23andMe data). One of the first things I’m told is that my eyes are green (they’re brown). However, the bioinformatics got my skin type and frame/weight generally right and had interesting (albeit occasionally generic) things to say about exercise, diet, goals, steering clear of too much sugar and so on.
The most important part of this process is registering your kit before shipping it. All five services require this, and if you don't do it, you won't be able to access your results. This requirement is to protect your privacy—your name won't appear on the kit or the results—and to easily track your kit as it goes through the process. Of course, when you sign up for an account with these services, your identity will be associated with it, but the sample and any reports stored on the service's end will just have a unique barcode.

It is very important that you take the time to read the privacy policy, terms and conditions and consent forms associated with any DNA test you take or any site you choose to upload your data to. While FTDNA has a proven track record of protecting the privacy of its users, there have been serious concerns over how AncestryDNA and 23andMe have used data in the past, as well as how they may use or sell your data in the future. Please read this article from Roberta Estes for more information on this issue. MyHeritage states that their consent form (that would allow sharing or selling of your results in aggregated data) is optional.  You can read more about that on The Legal Genealogist, who compliments MyHeritage DNA on their policy and openness.
Alternatively, if you believe your "Italy/Greece" result indicated your known Italian heritage, it is possible that your son simply did not inherit the associated DNA from you. We all inherit roughly half our DNA from each parent, but the DNA we inherit is selected at random, and so even full siblings can have different ancestry results, depending on which genetic variants they inherited.
A. As stated above, the NHS in the UK does not offer genetic testing for establishing biological relationships. Here at DNA Clinics, we pride ourselves on the clinical and ethical approach we provide for our DNA testing service. DNA Clinics may consider offering free DNA testing to individuals or families who consent to having their 'story' and experience of the DNA testing process published or reported in the media. This will only be considered for appropriate situations. Please call 0800 988 7107 for further information.

Which is all very well, but do these kits work and deliver the service they promise and what about the wider ethics and implications of home genetic testing? Is it always wise for generally under-informed, under-prepared consumers to meddle in the highly complex, nuanced arena of genetics, risking confusion, complacency or even outright panic and anxiety when confronted with ostensible “bad news” (which may not even be true)?
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.
Because it is a genetic condition, hereditary hemochromatosis is present at birth. Many people with this condition never develop iron overload. Of those who do develop iron overload, only a small number develop symptoms. If men develop symptoms, they typically appear between 40 and 60 years of age. Women rarely develop symptoms, and when they do it tends to be after menopause.
Every human carries two copies of the genetic code, one inherited from the mother and one from the father, some 6 billion letters in all. Apart from identical twins, no two individuals have the same genetic code.  With the exception of the egg and sperm cells, all the cells of our bodies have 23 pairs of chromosomes, 46 in all. One chromosome of the pair is inherited from the father and one from the mother. However, in males the 23rd pair consists of a so-called Y-chromosome and an X-chromosome, whereas females have two X-chromosomes.  The Y chromosome contains a gene which triggers embryonic development as a male and carries information about the male’s paternal lineage.