Since its discovery 20 years ago, the use of DNA for human identity and relationship testing has emerged as a powerful tool in both civil and criminal justice systems. DNA testing can reveal whether two or more individuals are related as well as determining the nature of their relationship. Today, it is possible to identify people by a single hair, as well as obtain information about their gender and ethnic background, and, within the next couple of years, identify their age.
Before the advent of DNA testing, human identity testing was largely carried out through blood typing. DNA analysis has now superseded blood testing and is the most accurate method currently available for human identification.
How DNA Testing Began
The possibility that DNA could be used for human identity and relationship testing had been discussed from the time DNA was first revealed as the molecule which makes people unique. Yet, it was not until the discovery of DNA fingerprinting by Prof. Alec Jeffreys (now Sir Alec) of Leicester University in 1984, when the first practical testing system became available. As with conventional fingerprinting, where various loops and whorls are compared between two fingerprints, DNA testing relies on comparing certain DNA features called DNA markers between two individuals. If DNA patterns between the samples are identical, then they are likely to come from the same person. If the profiles are not identical but big similarities are observed, then the samples most probably come from related individuals. The degree of the similarity between DNA profiles is a representation of the degree of relatedness between people.
The Applications Of DNA Testing
Currently, DNA testing is routinely used for both criminal and non-criminal applications. However there is a major difference between DNA testing for civil and for criminal cases. For civil cases, DNA testing is predominantly used to determine relationship between individuals while for criminal cases a crime scene stain has to be matched to the suspect.
In non-criminal legal practice, DNA testing is used primarily for immigration and child support cases. In 2009, more than 17,000 DNA tests were conducted for these purposes in the US. Where no reliable documentary evidence is available, DNA testing can assist in determining varying degrees of relatedness between individuals concerned, as well as individuals ethnic background.
The first time DNA testing was used for identity purposes was in the landmark immigration case Sarbah vs. Home Office (1985). In this case, DNA testing was used to prove the mother-son relationship between Christiana Sarbah and her son Andrew. Now, the courts accept DNA testing as a virtually unquestionable proof of relatedness. The results will normally (although not invariably) provide conclusive evidence as to whether individuals in question are related as alleged.
The US Child Support Agency extensively uses DNA testing for establishing who the biological parent of the child is for purposes of providing child maintenance and support. Child support is one the main areas of non-criminal DNA testing.
Child adoption is another area where a DNA test for paternity, is widely applied. Currently, adoption agencies adopt children into families which match their ethnic background. Sometimes, it is difficult to determine the ethical background of the child and here DNA testing can help. People of different races and ethnic groups have common facial and other features which are typical for this particular race or group. The same is also true for their genetic characteristics. Various racial and ethnic groups have genetic markers specific to these groups. When analyzing these markers, it is possible to tell the proportion of individuals ancestors who came from specific ethnic groups. It is, however, impossible to pinpoint at what stage the particular ancestors contributed their DNA and also their number. For example, the results of ethnicity DNA testing can show that an individual has 20% of markers specific to northern Europe, 50% to the Middle East, 10% to the Mediterranean and 20% to sub-Saharan Africa. Using this information the family with the closest ethnicity to the child can be chosen.