All About DNA Paternity Testing

DNA testing/fingerprinting refers to the process of examining an individual’s DNA markers for the purpose of genetic human identification and for determining the relationship between two people.

DNA is located throughout the human body in the same identical form i.e. the DNA in the blood is the same as that in the skin, cheek lining, muscle, bone, teeth and various other tissues. So, the test sample (DNA) can be obtained from any of the sources like buccal swabs, hairs, saliva, blood, liver tissues, etc. Half of the DNA content of a child is inherited from the mother and rest half from the father and this DNA remains totally constant throughout life.

During the paternity testing process, the genetic characteristics of the child are first compared to those of its mother. Those characteristics in the child that cannot be found in the mother have been inherited from the biological father. If the tested man (alleged father) does not have the genetic characteristics necessary to be the biological father of the child, he is excluded. If the tested man’s DNA does contain those genetic characteristics, then the probability that this man is the true biological father is calculated and reported by the laboratory.

The DNA paternity test is the best test for solving the paternity cases with an extraordinary accuracy. The genetic profiles generated in the laboratories are admissible in court and can be presented as a proof of parentage. It is possible to perform the DNA paternity test without mother DNA samples, just by comparing the DNA samples of child and alleger father.

DNA can be classified into three types for paternity identification purposes:

Autosomal STR: These are the short tandem repeats found in the autosomal DNA i.e. DNA molecules other than X and Y chromosomes. These STR are highly variable regions lengthwise and vary from individual to individual. The size of the STR is what scientists look at to help answer questions regarding relatedness.

Y-chromosomal DNA: Y-chromosome is exclusively contributed by father. This helps in predicting the paternal line & helps in establishing ancestral relationships on father’s side. Mitochondrial DNA: Mitochondrial DNA is exclusively contributed by the maternal ovum. This helps in following the maternal line back in time. It helps in establishing ancestral relationships on maternal side.

DNA Testing can be applied in many cases like:

Prenatal and Newborn Paternity Testing
Identification of deceased alleged father
Identification of sibling relationships
Criminal Paternity
Genetic Reconstruction or Reverse Paternity
Presence at crime scene

Sometimes, two individuals, who are suspected to be the alleged father of a child, may show similar results. In these cases, DNA of both individuals is compared to the DNA of the child and the relative probability of the matching DNA fragments is calculated. The one with higher probability is taken as the biological father of the child. In such cases, accuracy of the test reduces.

Usually people are afraid of their DNA testing results going public. To eliminate such a possibility, legal law enforcement ensures that any DNA Testing results can NOT be made public, by any laboratory, without proper consent from the individual who takes the test.

The biggest advantage of DNA testing is that it can’t be cheated in any possible way!