DNA Profiling
The DNA of an individual is very nearly the same in each and every somatic (nonreproductive) 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 both their parents in roughly equal amounts. This genetic material is known as the nuclear genome of the individual, because it is found in the nucleus.
Comparing the DNA sequence of an individual to that of another individual can show whether one of them was derived from the other. Specific sequences are usually looked at to see whether they were copied verbatim from one of the individual's genome to the other. If that was the case, then the genetic material of one individual could have been derived from that of the other (i.e., one is the parent 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.
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 prove only if two individuals are related by common descent through maternal lines only from a common ancestor and is, thus, of limited value (for instance, it could not be used to test for paternity).
In testing the paternity of a male child, comparison of the Y chromosome can be used since it is passed directly from father to son.
In the US, AABB has regulations for DNA paternity and family relationship testing, however, AABB-accreditation is not necessary. DNA test results are legally admissible if the collection and the processing follows a chain of custody.
Read more about this topic: Parental Testing
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