Whether you purchase a home DNA testing kit at the drugstore or order a kit from an online vendor, you can obtain specific information about your genetic makeup in the privacy of your own home. All you have to do is follow the instructions in the kit, which typically includes buccal - or cheek - swabs and a return envelope. Use the swabs to sweep the inside of the cheek of each person being tested to gather DNA samples and send them to the testing lab in the envelope provided. The required lab analysis is done promptly, and within a short time you'll receive your results by e-mail or postal mail.
Home DNA testing kits are most commonly used to determine paternity, that is, who is or isn't a child's father. Buccal swabs obtained from the child and the alleged father are tested to determine the probability of a biological relationship. Three results are possible: inclusion, exclusion and inconclusive.
- Inclusion means that there is sufficient matching of loci (locations on the strand of DNA) from each person to conclude that the adult male is the child's father.
- Exclusion means that there is insufficient matching to prove a father-child relationship.
- Inconclusive results can be the result of too-poor quality or insufficient amounts of DNA in the samples to warrant drawing any reasonable conclusion about paternity.
Although the FBI's acceptable minimum number of matching loci, or markers, for inclusive results is 13, which is also generally the global standard, many private labs test for 16 or more matches. In fact, the more markers that match, the higher becomes the probability of paternity. Inclusion results indicate a more than 99 percent probability of paternity, while exclusion results show a 100 percent probability of no father-child relationship.
Although there is no difference in the testing process, test results you plan to use in court or other legal proceeding must carry proof of the chain of custody: A third party must collect the samples and you must provided proper identification. Chain-of-custody testing kits cost more than basic in-home test kits.
Home testing kits can also be used to determine the probability that someone is at risk for genetic disease or adverse drug reactions, and that individuals are twins - fraternal or identical - siblings, cousins, aunts, uncles or otherwise related. Not all labs or store-bought kits include services other than paternity testing.
If you are researching your family tree, you can obtain your personal DNA profile through a home testing kit and later compare it to another person's profile to determine if you are related to someone sharing your surname or you're descended from a president, famous writer or infamous scoundrel.
The American Association of Blood Banks serves as the accreditation agency for DNA testing labs. Members of AABB comply with the high standards set by the agency, thus providing assurance to their clients that their testing process and results are thorough, accurate and reliable.