How a Paternity Test Works
Paternity testing is the basic term used for determining the father of a child. Because everyone is born with a specifically unique DNA structure (the building blocks of life) whose characteristics are related to their parents’ DNA structure, determining parentage is a simple and definitive process. The testing of DNA has become the generally accepted method of determining paternity.
Types of DNA testing
There are two main types of DNA testing that are used in paternity testing. One is PCR which takes a section of the DNA from the sample given from the donor and then these same sections are produced by a lab and highlighted with fluorescent tags to show sections that will be compared.
A second type of DNA testing, with RFLP, takes the DNA sample and uses enzymes to break the DNA sections apart so that an electric current can be used to segregate the DNA by size. They are then identified by the use of DNA probes that allow the DNA to be identified more easily.
Where can DNA be found?
While there is DNA is nearly every living cell in a body, most testing is done with either blood or saliva samples. These tend to yield the highest concentrations of DNA that can be sampled and then tested. The most common route is to take saliva from both the child and each of the parents and then compare the DNA that is isolated from those samples.
What is the testing process like?
Scheduling an appointment with a physician or genetics counselor can start the process of determining the paternity of a child, in a more formal case, or a test can simply be performed from the comfort of your own home. In either case the actual time it takes to obtain the sample is minimal. Using sterile swabs, the mother, father, and child will all collect saliva samples from the inside of their cheeks. The collected samples are then sent to a paternity testing laboratory where the samples are run through one or both of the processes that were previously mentioned and the DNA markers are established. By identifying the DNA profile, the lab can then see if there are enough similarities between the child and the father in order to establish a clear paternity. The time to complete the testing once a sample reaches the DNA testing lab is usually about three days.
A much less common type of test is a pre-natal paternity test which is performed on an unborn child. Such a test must be performed in a sterile medical environment and as such requires a physician's approval. Because the DNA sample collection posses a small risk to the unborn child a physician may recommend against having the test performed at that time unless there is a good reason for doing so.
Are at the tests accurate?
Most at home tests can have a reliability of up to 99% because they employ the same methods and sampling techniques as a physician’s office, although care must be taken to carefully collect the samples and ensure they are kept sterile. However, as long as the samples are collected in a controlled manner, at home paternity testing can have reliability on par with that of that done in a physician's office setting. Note that in many cases in order for the test results to be admissible in court the paternity test must be performed in a doctor's office in order to ensure the samples were collected in the proper manner. If court admissibility of the results is a concern for you, check with your local municipality to understand their guidelines.