Principle of the paternity test
Today, DNA analysis is the standard method of ascertaining paternity or other kinship. DNA can be easily attained without the need for blood withdrawal, most often through swabbing the oral cavity. DNA is isolated from saliva of the presumed father and child, in some cases from the mother. Isolated DNA is subjected to an enzymatic reaction, through which previously defined genetic markers are selectively replicated. These markers form a characteristic genetic profile that is genuine for each human being and, with the exception of single-egg twins, it is impossible for two individuals to have corresponding results.
The principle of determining paternity is based on the comparison of the child’s genetic profile with that of presumed father. If, upon comparison, a combination of markers is found in the child’s profile that the presumed father does not have, paternity can be excluded with 100% certainty. If the child’s and presumed father’s profiles show a match, paternity can be confirmed with a certainty that is close to 100%. The more markers that are traced simultaneously, the more probable it is that such a confirmation’s certainty will approach 100%.
Besides determining paternity, which is most frequent, it is possible to confirm or exclude other types of kinship through DNA analysis. Mostly, comparison is made between one relationship and another, for example, ascertaining the consanguinity of siblings, etc. Under certain conditions, these tests can be performed upon missing or deceased persons if a sample of their DNA, such as hair, clothing, etc. can be attained.
Identification testing is another possible application of DNA analysis. It is most often used in criminalistics in the confirmation or exclusion of sample matches from the crime scene with samples of suspects. Further, this test is used in ascertaining the identity of victims of tragic accidents, events of terrorism, etc.