Many people whose main aim is to find new family and who are looking to use DNA testing as an investigative tool might have already done some research on their family tree, may well have gone as far as they can by conventional means and have hit a brick wall but want to explore their ancestry further. For people in this category their aim is to find cousins that they were previously unaware of, make contact with them, share information about their common ancestors and see if they can to join up there family trees through known relatives or through the new investigative leads they gain from each other. The nature of the inheritance of the three different kinds of DNA means that, in general, testing the kind of DNA known as autosomal DNA is best for finding previously unknown family members because it can detect all strands of your ancestry and not just unbroken male and female blood lines.
Autosomal SNP Tests
There are three companies who provide this type of DNA service, all at $99 per test (plus shipping): 23andMe, Family Tree DNA and AncestryDNA (ancestry.com). All are based in the US but 23andMe and Family Tree DNA offer the same service to customers globally. Like all tests that try to connect related people, it works by comparing your results with those held on a database containing all the individuals that have been previously tested using powerful software to search for close matches. If there are significant similarities in your DNA with other people you will be given the chance to contact them by email to explore your common ancestry.
As explained in Family Tree and DNA Inheritance, because we have many more distant cousins than we do close cousins, it is more likely, for example, that 4th cousin matches will be found rather than 2nd cousin matches and the more distant the relationship the less likely it is you will be able to share relevant information and connect your family trees. The chances of being given links to cousins with whom you share a recent ancestor is obviously dependent on how many of your extended and distant family have also been tested by the same company.
At the moment the majority of customers on all databases built up by the three testing companies are from the US although there are significant numbers globally particularly from Britain and Europe. Even for US customers the numbers of people on the SNP databases at the moment are small when compared with the total US population (databases contain between fifty thousand to a couple of hundred thousand people depending on the company) and so the chances that you will be connected with very close relatives is not great. In other words it is more likely you’ll be connected with 4th and 3rd cousins rather than 2nd cousins – and bear in mind that it may be difficult to discover a non-DNA connection with a third cousin as you are only likely to share one out of eight pairs of your great, great grandparents. Even still, I think these tests do offer excellent value for money because a) you may be lucky and connect with a close relative, b) you may very well be interested in more distant strands of your ancestry, after all it is part of your heritage, c) more and more people are taking the test, databases are growing quickly and the service you receive is ongoing in that you will continue to receive new connections when you match with new customers being added to the database (as long as companies continue to offer the current testing platform), d) the tests include fascinating information about your ancient biogeographically origins, in other words what world populations does your unique mix of genetic material originate from?
If you are willing to invest the resources and are keen to investigate all aspects of your DNA heritage either purely out of enthusiastic curiosity or because you have lost ties with your family through adoption and are keen to leave no stone unturned, Family Tree DNA have large databases containing Y-STR and mtDNA test results from large numbers of people and these can be searched for matches and possible links to relatives not unlike autosomal SNP tests, albeit with a lower chance of finding close relatives.