Genetic Reconstruction
Genetic reconstruction uses all the same techniques that a standard paternity test, such as the polymerase chain reaction to separate the relevant DNA sequences and replicate them, plus RFLP (Restriction Fragment Length Polymorphism) to amplify and dye the sample ready for human analysis. The main difference with genetic reconstruction is that it is carried out on a different set of people, other than the suspected father and the child in question. In this situation, the aim of a DNA testing laboratory is to create a set of DNA that the father is likely to carry, from relatives who are closely related to him.
The one individual always tested during a genetic reconstruction is the child whose paternity is in question. If the child's mother is able to give a sample then this effectively 'rules out' some of the child's DNA and laboratory professionals can concentrate on matching the remaining child's DNA (inherited from the father) with the close relatives of any alleged father. 'Close relatives' may seem like a vague term, but it in fact simply refers to the brothers and sisters or mother and father of the alleged father (i.e. immediate family). If both parents of the alleged father are available to give a DNA sample then instead of full genetic reconstruction a simple grand-parentage test can be carried out. This means getting DNA from the child and his or her alleged grandmother and grandfather and comparing the two samples. If they share specific similarities then it can be confirmed that one of the children of that couple is also the mother or father of the child. These people are guaranteed to share a certain percentage of their DNA with the individual in question and they will therefore share a smaller percentage with the child whose paternity is being tested for. By comparing the siblings and parents of one potential father with another's, and then seeing which family shares the most DNA with the child we can see which father is most likely to have paternity.
Unfortunately, likelihood is all that can be determined through genetic reconstruction. No DNA testing laboratory will ever tell you that one man definitely is or isn't the child's father, but they will tell you there is a higher likelihood that one particular man is the father than another. Having access to a sample of the child's mother's DNA will increase the certainty of the genetic reconstruction test results. The test results for genetic reconstruction usually take longer than a standard maternity or paternity test. This is because there are more DNA samples to be analyzed, so results are typically available between 3 and 6 weeks.
Genetic reconstruction is one type of DNA testing used when the person in question is not available to give a DNA sample. In this article we've focused on paternity testing when the father cannot give a sample, but this is also used in maternity testing and other situations such as when a child is adopted and suspects a deceased or missing individual is their parent.