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.
Men have an X and a Y (chromosome) that are paired together. Women don’t have the Y, they just have two X’s. A child’s genes come from a mix up and recombining of the two parents. So a girl child will still end up with two X’s but some bits of them will come from the father’s X and some from the mother’s. A boy child on the other hand may have some bits of X from both mother and father, but his Y will have just come purely from his father – virtually unchanged. That makes Y-DNA such an exciting possibility for genealogy where you want to follow the paternal (surname) line. You could expect that Y-DNA will therefore pass virtually unchanged from father to son through the generations, meaning that the Y-DNA of a man’s g-g-g-g-grandfather will look very much like that of his own Y-DNA – with some little changes.
Specific tests for your father’s family include ‘Y-DNA’ tests which focus on the ‘Y chromosomes’ in your cells’ nuclei, passed down from father to son. Specific tests for your mother’s family include ‘mtDNA’ tests which report on a subset of DNA found in the ‘mitochondria’ (your cells’ energy factories), passed down from mother to son or to daughter.
After taking a DNA test for ethnicity, many ancestry companies will give you the option to contact their other customers, providing you share sections of your autosomal DNA with them (meaning that you’re related to these individuals to a greater or lesser degree). The companies that do this maintain ‘Family Finder’ databases, and the people you’re related to are usually referred to as ‘matches’. The three largest companies that do this are Family Tree DNA, Ancestry.com and 23andMe, and as part of the results that they provide, you’ll be able to see a list of these living relatives ranked according to how closely you’re related to them.
First of all, what is DNA? The letters stand for Deoxyribonucleic acid, a molecule encoding the genetic instructions used in the development and functioning of all known living organisms. Its structure was first described by Nobel Prize winners Crick and Watson in 1953. The information in DNA is stored as a code made up of four chemical bases: adenine (A), guanine (G), cytosine (C), and thymine (T). The DNA bases pair up with each other, A with T and C with G, to form units called base pairs. Each base is also attached to a sugar molecule and a phosphate molecule. Together, a base, sugar, and phosphate are called a nucleotide. Nucleotides are arranged in two long strands that form a spiral called a double helix. The structure of the double helix is somewhat like a ladder, with the base pairs forming the ladder’s rungs and the sugar and phosphate molecules forming the vertical sidepieces of the ladder.

We have zeroed in on autosomal tests only. These tests are used to give you the ancestry percentages and cousin matching most people are seeking. If you are interested in YDNA (paternal line only, for men) or mtDNA (maternal line only) you can find these tests at Family Tree DNA. 23andMe also offers limited motherline and fatherline results as part of this main ancestry test.
If you are interested in doing in-depth analysis, the firm offers a chromosome browser, allows raw data to be uploaded, provides support for setting different segment matching thresholds, and allows up to five comparisons to be done at once. Family Tree DNA allows trial transfers from 23andMe and AncestryDNA into its match database; additional transfers of various datasets is available for a fee. The company promises to keep data for 25 years.
As my dad and I have begun to explore our genealogy over the past seven years or so, we’ve found that our family is largely from Spain, which is no big surprise. Colombians have a wide range of ethnicities, which explains why many Colombians, including my mother, have white or fair skin with blue eyes. My dad also suspects we have German ancestry somewhere back there.
In McCartney’s view, enough testing is already done in this country (sometimes too much) and there are issues of regulation and “informed consent”. “People are given very dramatic reasons to have these tests – it could help save your life, it could help improve the quality of your life – but where is the actual controlled evidence that these tests have ever done that? There’s no evidence that says doing these tests makes people become healthier.”
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.” 
To prepare to take a cheek swab sample, you also have to refrain from eating for about an hour before. Swab kits generally contain more components, including one or two swabs and containers to protect the used swabs from contamination. We found it easiest to organize all the pieces first, to prevent any fumbling with a sample collection swab in hand. Some cheek cell kits put a stabilizing liquid in the sample containers, which required extra caution to prevent spilling.

It is very important that DNA evidence is examined by a suitably experienced and qualified scientist who is able to critically evaluate the DNA results themselves and also to consider their significance in the context of the particular case being considered. This is particularly so in the case of mixed DNA profiles, which may be complex, and in the case of DNA profiles obtained using Low Copy Number or other highly sensitive techniques which may be open to subjective interpretation.
In addition to showing geographic ancestry percentages, some direct-to-consumer DNA tests also include insights about physical traits like hair and eye color. With 23andMe, this trait information is mostly available in the upgraded Ancestry + Health kit, but some interesting tidbits can be found in the Your DNA Family report, which is available if you opt to participate in the DNA Relatives service. 
Although, I have absolutely no British or Irish ancestry, I found my results extremely satisfying. I particularly appreciate that living DNA gives you a lot of ways to view your data. You can see your ancestry results as color-coded dots filling up a person’s silhouette, on a map, as a pie chart or on a timeline. All the graphics present the same set of data, but each has its own appeal. Within each graphic, you can also choose to view global or regional matches and cautious, standard or complete estimates, which each have a different level of detail and certainty.
Men have an X and a Y (chromosome) that are paired together. Women don’t have the Y, they just have two X’s. A child’s genes come from a mix up and recombining of the two parents. So a girl child will still end up with two X’s but some bits of them will come from the father’s X and some from the mother’s. A boy child on the other hand may have some bits of X from both mother and father, but his Y will have just come purely from his father – virtually unchanged. That makes Y-DNA such an exciting possibility for genealogy where you want to follow the paternal (surname) line. You could expect that Y-DNA will therefore pass virtually unchanged from father to son through the generations, meaning that the Y-DNA of a man’s g-g-g-g-grandfather will look very much like that of his own Y-DNA – with some little changes.
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