A DNA sibling test helps to compare the DNA of one person to that of another person to know whether they are related biologically as siblings or not. In most cases, sibling tests are performed to get to know about paternity. This often happens in situations where the possible father is unavailable to participate in a paternity test.
If you see in a legal way, sibling DNA test results are also preferred by a woman to obtain Social Security survivor benefits for her child. In this type of case, the biological father of one child is not in doubt and the mother needs to prove that the other child has the same father.
Sibling DNA tests are also very helpful to provide evidence of biological relationships for U.S. immigration. In some cases, where a child was given up for adoption, a sibling test may also be performed to address whether another individual (perhaps tracked down many years later), has the same biological mother.
In a sibling DNA test, the degree of certainty depends upon who is available for testing as well as the specific type of sibling relationship being tested. In other words, you can say that the more genetic information available, the greater the chance your DNA test will be conclusive.