How Does DNA Profiling Work?


Quick Answer

DNA profiling works by mapping the section of an individual's genome that varies from that of other people in the population. Since most human DNA is identical, only a relatively small section of the total genome needs to be sequenced to achieve a positive identification for paternity, forensic or archaeological purposes.

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Full Answer

The process of DNA profiling begins with the collection of a sample. The sample can be evidence left at a crime scene, residue recovered from an archaeological dig or a cheek swab from a child with uncertain paternity. This sample is then subjected to laboratory processes, such as polymerase chain reaction, to amplify the size of the sample and make sequencing easier. The targeted sections of the sample DNA are then sequenced, resulting in a linear chain of nucleotides unique to the individual, and matched with another sample, such as may be collected from a potential father, long-lost relative or criminal suspect. The two sequences are then directly compared for their degree of similarity. Sometimes, as is the case with paternity testing, a sample of the mother's DNA is used as a control to isolate only the father's DNA for the test. If the genetic similarities are significantly closer between samples than chance alone would predict, the DNA profiles are a match.

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