Paternity Tests and Testing

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.

Proving paternity can be achieved by DNA test analysis of the three individuals involved, although older methods have included ABO blood group typing testing, tests analysis of various other proteins and enzymes, or tests using HLA antigens. The current techniques for paternity testing are using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). For the most part however, DNA has all but taken over all the other forms of paternity testing.

The DNA of an individual is almost exactly the same in each and every somatic cell. Sexual reproduction brings the DNA of both parents together randomly to create a unique combination of genetic material in a new cell, so the genetic material of an individual is derived from the genetic material of their parents. This genetic material is known as the nuclear genome of the individual, because it is found in the nucleus.

Proving a relationship by comparing the mitochondrial genome is much simpler method than those tests based on the nuclear genome. However, testing the mitochondrial genome will only prove if two individuals are related through maternal lines, from a common ancestor and is therefore of little value and could not be relied on as a test for paternity.

Comparing the DNA sequence of an person to that of another person can show if one of them was derived from the other or not. Specific sequences are usually looked at to see if they were copied from one of the person's genome to the other. If that was the case, then this proves that the genetic material of one person could have been derived from that of the other. Besides the nuclear DNA in the nucleus, the mitochondria in the cells also have their own genetic material termed the mitochondrial genome. Mitochondrial DNA comes only from the mother, without any shuffling.