DNA Sibship Test

Analysis of the DNA of two separate individuals can provide information as to whether they are full siblings, half siblings, or not related. Please read the information provided below to fully understand the benefits and limitations of the sibship test before ordering.

Understanding Sibship Testing
When the issue of sibship is in question, the recommended method to determine whether individuals are true biological siblings is to test their parents. DNA paternity and maternity testing will provide conclusive results. However, in situations where the alleged parents are unavailable for testing, a DNA sibship test can be performed to analyze the relationship of biological siblings.

When a sibship test is conducted, the DNA laboratory will determine the genetic profiles of the alleged siblings. Based on the type of genetic material inherited by each sibling, a sibship index is determined. If the sibship index is less than 1.00, this indicates non-relatedness. If the sibship index is greater than 1.00, this indicates that the two tested individuals are more likely to be true biological siblings. The higher the value of the sibship index, the greater the likelihood that the two individuals are true biological siblings. To analyze the possibility that the siblings share only one common parent versus two common parents (mother and father), a half sibship index is obtained. The ratio of the half sibship index versus the full sibship index will indicate whether the two individuals are more likely to share only one common parent (e.g. mother only) or two common parents (mother and alleged father).

A sibship test will help to provide you with an indication of whether you are more likely to be or not to be the true biological sibling of the other tested individual.