The use of DNA testing for determining a person's ancestry is becoming more and common. By linking your maternal DNA (mitochondrial DNA) and your paternal DNA (the y-chromosome), these ancestry databases are effectively able to link you to other people to whom you may be related and thereby determining to some degree your ancestral lineage and where your ancestors came from.

The first thing that genealogists look for is a father-to-son linkage, tracked down the Y chromosome which only men posses. Therefore, they are able to observe the Y chromosome that appears in other people and compare them, to determine where a paternal link may be present. This comparison, in essence, allows for the genealogist to try and find paternal linkages amongst people. The other thing that can be done is to link maternal DNA. This in particular is a very powerful testing method that allows for accurate tracking back over many generations because of the mitochondria.

Unlike DNA found in the nucleus, which can be altered and changes as environments change, mitochondrial DNA is a direct connection from child to mother that can't be altered along the way. By taking a sample of the mitochondrial DNA, which is different than the DNA found in the nucleus, the genealogist can determine a maternal linkage. By taking this information, they can, once again, find, perhaps those long lost cousins or celebrity ancestors.

However, can this really be effective at tracing family lines? How can they tell you who you're related to throughout history? Some online ancestry websites create a database of DNA against which your can be matched. By taking a simple mouth swab and run the DNA tests, they then save the DNA profile that is collected. However, the key is for them to continuously compare other people's DNA profiles to what your profile is. In essence, this will create a massive database that will determine instantly if a piece of code is a direct comparison to yours. So, as the database grows more and more, more and more relatives and ancestors can be discovered for more and more people.

Furthermore, these DNA tests are able to help you find out where you come from. It's argued that 170,000 years ago, humans left Africa and migrated elsewhere across the globe. Some went to Europe, some went to southern Africa, while others went to Asia to settle. By comparing the DNA profile of a person to that of researched ethnic groups, it is possible to provide information about where people are from.

DNA testing has become a very useful method for people to find long lost relatives. Furthermore, the argument of the true nature of one's ethnic origins can finally be resolved by DNA testing processes. Of course, as the databases grow and more research is conducted on, the usefulness of these types of tests will increase greatly.