HomeDNA has the simplest DNA extraction process; just swab each cheek twice with a cotton swab, and place the swabs in the included envelope. The National Geographic Genographic Project sent a scraper that you use on each cheek for 45 seconds, and then place in a vial with stabilizing liquid. MyHeritage DNA has a similar process. 23andMe and AncestryDNA require that you spit into a tube up to the fill line (harder than it sounds), and ship it back with stabilization liquid. Most of the services said not to eat, drink, or smoke for 30 minutes to an hour prior to testing to get the best possible sample.

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.”
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.
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?
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.
1. Family Tree DNA’s Family Finder: One of the first to offer these types of tests, FTDNA is generally considered the leader in autosomal DNA testing for ancestry and provides some of the best tools available for genealogists. Their population finder section is currently a bit less specific than the other companies, but FTDNA Family Finder users are eagerly awaiting a much improved update to be released sometime in the next month. Find out about Family Finder here.
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