Sibling genetic relationship test

What is the purpose of a DNA-based sibling test?

The sibling test conducted by the DNA Center helps determine whether two individuals are full siblings, half-siblings, or not genetically related. This test is typically requested when the alleged father is unavailable for a paternity test, and the siblings or another interested party wish to determine whether they share one or both biological parents.

Sample collection is simple and can be performed at home using the kit sent by mail. The samples can then be returned to the DNA Center by mail or delivered in person to our clinic.

What types of sibling tests are available?

The DNA Center offers two types of sibling tests:

• Half-sibling test: This test determines whether two individuals share at least one biological parent. For example, if they are known to have different mothers but want to know if they share the same father.
• Full-sibling test: This test determines whether two individuals share both biological parents. For example, if they are known to have the same mother but want to confirm whether they also share the same father.

Who can participate in a sibling test?

A sibling test requires the participation of at least two presumed siblings. If more than two siblings are tested simultaneously, one person must be designated as the reference, against whom the genetic relationship of the others is compared.

The inclusion of the mother or mothers in the test greatly simplifies the analysis. If the mother's DNA sample is available, the laboratory can "subtract" her genetic markers from the child's sample, focusing solely on the paternal markers. Although including the mother’s DNA is not mandatory, it can significantly facilitate the analysis. If the mother(s) are unavailable, the test can still be conducted, but the analysis may be more complex.

What results are provided by the sibling test?

The results are presented as a combined sibling index, indicating the likelihood that the tested individuals are siblings. Since sibling tests are more complex than paternity tests, the results can sometimes be less definitive.

The analysis typically takes around 10–12 days, and the results are sent to the client by mail and/or email, depending on their preference.