Sibling DNA Testing is used to provide the probability of genetic relationships between two people, specifically when no other relatives are available for testing. The sibling DNA testing is divided into two categories
This test is ordered for clients who want to determine if they have both parents in common (share the same mother and the same father)
Father is missing and two individuals know that they share the same mother but are not sure if they have the same father. This test would determine if they have both the same mother and father.
The test is ordered for clients who want to determine if they have one parent in common. (Share the same mother or the same father)
Once your extended relationship testing is complete, you will be provided with a report that lists the number of genetic markers (loci) that were tested. You will also be provided with an explanation of the results. The first term is the combined relationship index, where the relationship could be sibling, uncle, cousin or grandparent. This is a measure of likelihood suggesting that an individual whose relationship is unknown is more or less likely to be the biological relative of another individual than another random untested unrelated individual. For example, if a combined full-siblingship index of 200 is determined, then this indicates that John Doe is 200 times more likely to be the biological full-sibling of Jim Doe than another random individual.
Generally values greater than 100 are very supportive of a true relationship, however, values even as low as 2 may still give evidence that a relationship exists. These values can be greatly enhanced by the addition of other known biological relatives that are relevant to the case. The second term that is provided is the relationship probability. In the case of siblings this will be provided as the Probability of Siblingship. Probabilities that are greater than 99% are strongly indicative of a true biological relationship, however, lower percentages may also indicate that a relationship exists and may support the available conventional genealogical records.
Likelihood indices and Probabilities of Relationships may be greatly enhanced by the addition of more loci (determined by the laboratory), provision of known ethnicities (determined by the client), or the addition of more known relatives (determined by the client through consultation with the laboratory).