Relationship testing is based on the fact that every related person shares some genetic information with another related individual. The closer the relationship is, the more genetic information will be shared. For example full-siblings will share on average 1/2 of their genetic makeup. This fact holds true since humans inherit 1/2 their DNA from their biological mother and 1/2 their DNA from their biological father. If we look at 1st cousins, they will share on average 1/8 of their genetic makeup. All calculations for relationship testing are primarily based on this sharing.

The second factor calculations are based on is how common or rare the shared DNA patterns are in a relevant population. Each identity marker we look at has been documented with thousands of random samples from different populations. For example, two Caucasian individuals who shared a genotype which 32% of the Caucasian population possessed, would be less determinate than if they shared a genotype that only 4% of the of the Caucasian population possessed.

For the above reasons, relationship testing in some cases may not be as determinate as a direct relationship analysis such as paternity testing. In most cases an acceptable answer based on population statistics will be concluded. In rare instances the result is not as determinate as desired. For example: Sibling-A is the full biological brother of Sibling-B with a probability of 73.3667% as compared to a random individual from the relevant race. When a result is reported as in the example, results are subject to individual interpretation. Unfortunately, there is no method of determining which relationship will be very determinate and which will not, until the genetic reconstruction is completed. Please keep this fact in mind when contemplating a relationship DNA test. We disclose this fact to you for your consideration before initiating any type of relationship testing.