A sibling test can be used to identify whether two, or more, children share the same biological parents. The analysis undertaken will also identify if they are related and if so whether they are Full Siblings who share both parents, or Half Siblings who share only one.
Sibling analysis is not as conclusive as paternity testing. The results will provide a statistical likelihood of whether two individuals are true biological relatives, but sibling analysis cannot provide a conclusive result. However, if either of the parents of the siblings who are being assessed are available for testing, this will aid the analysis and may increase the certainty of the result.