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.
The last ancestry-related report from 23andMe is your DNA Family. This report is separate from the relative matching feature, which you have to opt-in to. It tells you very generalized information about the people in the database who share segments of DNA with you, including states of residence, similar geographical ancestral regions and traits like the ability to wiggle your ears or whistle.
As with traditional genealogical research, DNA testing can provide surprises so be prepared for the unexpected. You might uncover family secrets by matching with a cousin or a half-sibling that you didn’t know existed. Conversely a relation who is expected to share DNA with you might turn out not to be a genetic relative at all. In rare cases, people discover that their parents are not their biological parents. For a good overview of the ethical implications of DNA testing see the Genetic Genealogy Standards.
Home DNA testing has gone from a niche pursuit to a simple way to map out your family tree. A DNA test can be used to determine paternity and research ancestry or familial origin. And over the past few years, they've become quite affordable, with a wide range of companies selling DNA test kits -- from trailblazers such as Ancestry and 23andMe to upstarts that include LivingDNA. 

DNA profiling can also be useful for those who suspect there may be inheritance disputes over their estate once they have passed away. It provides a record that can be referred to long after someone’s death, even when all physical traces of DNA have gone. Therefore, if there is an unexpected claim for inheritance from an alleged relative, your DNA profile can be compared to that of the claimant to prove or disprove a biological relationship and the inheritance rights.

For the uninformed, this is the best discussion on the subject of DNA that I have ever seen. I have been trying to determine who my great great grandfather is for years. I’ve tested with Ancestry and Family Tree DNA, hired ProGenealogists with Ancestry (twice), and still can’t determine who he is. I truly don’t know where to go now. The genealogist that consults with Finding your Roots works for a company that doesn’t do individual research. Who else does the genetic genealogist research that they do?
Prices range from £100 to £200 for a basic DNA profile, but it’s worth mentioning that the cost largely depends on what you intend to do with it. One of the major factors that you need to consider, and which significantly impacts the cost, is whether you want your DNA profile to be legally admissible or not. Legal DNA profiles cost more than peace of mind versions, but if there’s a chance that your profile will be used in legal proceedings, it’s worth paying extra for.
Costs vary depending on the company you buy from. For example, the three most popular DNA ethnicity tests are undertaken by 23andMe, Family Tree DNA (FTDNA) and They all analyse autosomal DNA to report on your ethnic mix: 23andMe’s costs £149, FTDNA’s (named the ‘Family Finder’ test) costs £60 and’s (named ‘AncestryDNA’) costs £79. However, it’s worth bearing in mind that 23andMe’s test also includes a Y DNA analysis and a mitochondrial DNA analysis, so if you’re interested in your paternal and maternal lineage (discussed below), this may be the more cost-effective choice!
My favorite DNA test for finding ethnicity is Ancestry DNA.  My second favorite is 23 and Me.  The way Ancestry presents their DNA results is easy to understand, and their test is general less expensive than 23 and Me.  I have also found Ancestry DNA’s ethnicity estimates very closely represent what I have been able to research the old-fashioned way, both in my family and that of my husband and other family members.

MyHeritage shows cousin matches as part of your DNA purchase for free and has some really wonderful tools to connect your research to your DNA matches. Using smart matching features to see how your tree is connected to others, and adding records you discover this way, may cost an additional monthly fee however. Still, MyHeritage is generally less expensive than Ancestry. You can also try their record collections for free here.
We evaluated each kit by ordering one, just like any customer would, and tracking how long it took to arrive at the lab and to get processed. Then we compared the breadth and depth of the results to see what rose to the top. The whole process was a lot of fun, in part because of the anticipation of getting the results. Most of the kits warn that testing your DNA can lead to surprising—even life-changing—results. For example, there's the story of a woman who thought she was Irish, but her DNA test revealed she was also European Jewish, Middle Eastern and Eastern European. After diligent research, she discovered that her father, who had died years earlier, had been switched at birth with another child.
Kits are despatched within 5-7 days of purchase date. The delivery time for your kit will vary depending on the postal service you have selected. Once you receive your kit, follow the simple instructions to activate it and send us your DNA sample. If you’re a new or returning Findmypast customer, you’ll receive a complimentary 14-day Findmypast subscription when you activate your kit.
MyHeritage DNA is the newest kid on the block and, while their database is still growing, it is comprised of people who have tested from all of the other three testing companies (this is thanks to their free DNA upload offer). In addition to this, they have shown a clear commitment to concerns and requests by their users by promising to provide advanced tools in the future and by creating an open and optional consent policy for use of DNA data. They also offer the ability to tie in with a large database of family trees and records. We think this test has a lot of promise if they continue to respond in this positive way to users.

DNA is a record of instructions telling the cell what its job is going to be. A good analogy for DNA as a whole is a set of blueprints for the cell, or computer code telling a PC what to do. It is written in a special alphabet that is only four letters long! Unlike a book or computer screen, DNA isn't flat and boring - it is a beautiful curved ladder. We call this shape a double helix. The letters of the DNA alphabet (called bases) make up the rungs, special sugars and other atoms make up the handrail.

Consult a doctor on any health data: Cancer. Leukemia. Heart disease. Alzheimer's. There are a lot of scary afflictions out there, and your DNA testing may well indicate which ones to which you are genetically predispositioned. But the data from DNA testing exists in isolation. You should consult your doctor to explore the data from any of these tests. They'll help you determine how to implement any lifestyle changes or followup testing as a result, if it's worth doing so.
A friend of mine knew I had been working on my family history and bought me an AncestryDNA kit for my birthday. My results were surprising to say the least. I discovered I’m 35% Native American, 5% African and 29% from the Iberian Peninsula. This has drastically broadened the way I think about my identity and heritage. I feel connected to those parts of the world now and I’m excited to see how far back our records can go.
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. 

The reason that saliva works as well as blood (or hair follicles or skin samples) is that your DNA -- which is short for deoxyribonucleic acid -- is present in all of them. It's the basic genetic code present in all of your cells that makes up your key attributes, from the color of your eyes to the shape of your ears to how susceptible you are to cholesterol.
The spit is for one of the home genetic-testing kits I’m sampling. A growing number of these kits (brands such as 23andMe, DNAFit, Thriva, MyHeritage DNA, and Orig3n) promise to unlock the mystery of your genomes, variously explaining everything from ancestry, residual Neanderthal variants, “bioinformatics” for fitness, weight loss and skincare, to more random genetic predispositions, denoting, say, the dimensions of your earlobes or the consistency of your earwax.
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.
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.
What we would expect to find then in this example is that the two descendants of John show a very close match, and the two descendants of James also show a very close match (because we know from conventional paper based research that they are related). If all four match very closely, then that’s further evidence to add to our theory that John and James were really brothers. Not conclusive proof- but pretty solid evidence.