Generally, a paternity test is conducted to prove paternity, that is, whether a man is the biological father of another individual. This may be relevant in view of rights and duties of the father. In a similar fashion, a maternity test can also be carried out. Although the latter is less common of the two, because at least during childbirth, except in the case of a pregnancy involving embryo transfer or egg donation, it is obvious who the mother is. To ascertain the paternity, the DNA method is generally preferred.

How is DNA used in paternity testing?
There exists certain regions of human DNA which show variations between people. At each of these regions a person possesses two genetic types (known as alleles), one inherited from each parent. By looking at a number of these variable regions in a person a DNA profile is produced. And by comparing the DNA profiles of the mother and child it is possible to determine which half of the child’s DNA was inherited from its mother (maternal alleles). Thus, the other half must therefore have been inherited from the child’s biological father. .

Another approach which could be taken but which has a few limitations is testing the DNA using mitochondrial genome. Proving a relationship based on comparison of the mitochondrial genome is much easier than that based on the nuclear genome. However, testing the mitochondrial genome can only prove if two individuals are related by common descent through maternal lines only from a common ancestor and is thus of limited value.

How efficient is the testing?
DNA tests are also carried out to ascertain biological parents. The above process enables this process. If a man is not excluded as the father of a child, a “probability (or likelihood) of paternity” is reported. That figure is usually greater than 99.5%. .

It is never possible to prove 100% that a man is definitely the biological father of a child, as there is always a chance, however remote, that another man in the population may have DNA types which match that child. .

Nowadays, there are Home DNA Paternity Test kits available which help these tests to be conducted at home without visiting a hospital. But the accuracy of different home DNA paternity differ but they help in ascertaining to a great extent.