Our laboratory reports a Kinship test result as one of six ways, which are:
* Very probable: POR is 99% or greater
* Probable: POR is >95% to 99%
* Indication: POR is >80% to 95%
* Uncertain: POR is >20% to 80%
* Improbable: POR is >5% to 20%
* Doubtful: POR is 0% to 5%
Since kinship tests are used to identify second degree relationships, one must consider that these individuals do not share as much DNA in common as do a parent and child. For this reason, results are variable and, sometimes, an "uncertain" result could be obtained from truly biological second degree relatives. Full siblings, for example, are expected to share roughly 50% of their DNA in common. However, sometimes full siblings may inherit the exact opposite genes from their parents, which in a DNA test , could look like they are not biologically related. Say, for instance, that at Genetic Marker #1, the mother has the alleles A and B, and the father has the alleles C and D. So, their children could have either AC, AD, BC or BD. Then, say that sibling #1 has AC and sibling #2 has BD. In a DNA test, this would be a complete non-match. Also, if the genes that the siblings do share are common, or have a high frequency, in their given racial population, it may also look like they are not biologically related, or at least not "very probable" to be.
While kinship DNA testing is a very reliable tool for verification of biological family relationships, sometimes extended testing may be needed to obtain conclusive results. On the contrary, however, many times, kinship tests do conclusively identify family relationships.