DNA testing examines the genetic code that’s carried in every person’s DNA. The code can be found in the cells of any human material, from a drop of saliva to a smear of blood or a strand of hair.
DNA testing works by taking a sample of cells from the person who’s undergoing the test. Scientists isolate the DNA code that is at the heart of every single cell and carries the information which determines all of your physical characteristics, from your hair color and height to your chances of developing certain conditions.
If you use a home DNA testing kit, you’ll find all the instructions included. Usually, you’ll be sent a sterile tube to collect your saliva sample. It can be awkward to get enough spit for the test purposes. Some companies send a cheek swab that you rub against the inside of your cheek to get a sample of cells from there, instead.
Once you've collected your DNA sample, you'll seal it into the sterile package and use the included mailing package to send it back to the company. It usually takes a few weeks to get the results, but the time frame varies; it can be anything from 4 to 12 weeks.
When your results are ready, you’ll typically get an email inviting you to view the results online. Ancestry DNA companies have a dashboard that lets you explore your results.
Potentially, everyone could need DNA testing at some point. It can be used to check for genetic disorders or inherited health conditions, paternity testing, or ancestry testing to learn more about your origins and search for family members. DNA testing has been used by historians and archaeologists to learn more about skeletons found at historic sites. For example, when the body of King Richard II was dug up in a modern parking lot, his identity was finally confirmed after DNA tests with some of his modern-day descendants.
The process of filling out the DNA test can essentially be separated into 3 steps: collection, packaging, and results.
Paternity tests are used to confirm who is the father of a baby, child, or adult.
Genealogy or ancestry tests are used by genealogists to determine ancestral ethnicity and relationships.
Gene therapy DNA testing is most commonly used for parents before they try to conceive or for fetuses to check for inheritable genetic conditions or if an embryo is carrying any birth defects.
Forensic DNA tests are used by police at crime scenes in order to identify victims or find criminals after certain crimes.
Here are the key considerations to look for when you choose a DNA testing company or a DNA testing kit.
If you want a DNA test in order to learn more about your family and your origins, you have a few options. An autosomal DNA test checks only 22 out of the 23 pairs of chromosomes and can be used to compare DNA from both males and females, so it's best for finding a range of living relatives. It gets less reliable the further back you go because of autosomal DNA changes every generation, so it's only good for identifying up to third or sometimes fourth cousins and can only give reliable information back to your great-great-grandparents.
A mitochondrial DNA (mtDNA) test checks the tiny mitochondrial strands inside every cell. Both males and females inherit these mitochondria from their maternal line. It can be extended much further back in time because it doesn't change quickly. It gives very precise details about your ancestors and distant cousins – even your 48th cousin! – but only if they lie on your maternal line. It’s good for proving you come from a particular region, ethnicity, or family group but not for finding relatives.
Y-DNA testing examines only the genetic information in the Y-chromosome, which is only found in males. It also does not change quickly, so like mtDNA, Y-DNA testing is good for proving relationship to a common ancestor or checking relationship with another individual, but it only works along the male or paternal line. This also means that only men can do a Y-DNA test, although women could ask a close male relative to take the Y-DNA test and then share the results.
The price of the DNA test varies between different companies as well as depending on the type of test you take. mtDNA tests are the most expensive type of DNA testing, while autosomal DNA tests are the lowest cost and Y-DNA tests come in somewhere between the two. Although the tests are more or less the same, there’s a huge fluctuation in price between different companies so do compare prices before you buy. Some companies, like LivingDNA, offer a package of all 3 tests for a discount.
Most DNA testing kits are pretty straightforward, but some elderly or weak individuals can find spit tests awkward to use. In those cases, companies that offer a cheek swab for taking samples instead of needing a saliva sample could be easier.
Not every company offers the same range of reports. Very few genealogical DNA testing companies will include health and wellness reports. Most companies provide ancestral reports, which break down your family heritage, ethnicity, and which region of the world you hail from, although some are more detailed than others. Some also provide a chromosomal browser which lets you compare your genetic profile with that of others from around the world. You can also find cousin matching reports, which let you know if you have any matches with other people registered with the same service.
The type of test you choose affects the accuracy since autosomal DNA tests are less accurate the further back you go but mtDNA and Y-DNA tests remain reliable for dozens of generations. The biggest DNA testing companies such as Ancestry.com, MyHeritage, and LivingDNA are all pretty equally accurate in their test results. However, all companies warn that you shouldn’t use home DNA tests for detailed and critical genetic information like the risk of genetic disorders or of developing cancer.
As well as these considerations, there are a few extra features that are offered by some DNA testing companies. Some companies store your data indefinitely which means you can discover new family history information 50 years down the line. Others only store it for a certain number of years.
Another feature is the size of the database. The bigger the database of users, the better your chances of finding a match.
Some companies also permit you to upload raw genealogical data to their database so you can see if you have any matches without taking a test again.