Most of us know who are siblings are and that siblings share more DNA than do unrelated persons. But for various reasons, sometimes people require a DNA confirmation that biological relationship exists. DNA tests can confirm biological ties but will differ based on the relationship and gender of test participants:

Brother’s Y Test

The Y chromosome is passed from father to son. By testing the Y chromosome in two brothers it can be determined if they have the same father. This DNA test is 99.9% accurate and it can be used to test a variety of male relations such as grandfather-grandson or uncle-nephew.

Sister’s X Test

Men have one X chromosome which they pass to all their daughters. By testing the X chromosome in two sisters it be determined if they have the same biological father. This DNA test is 99.9% accurate. This test is works best for sisters with different mothers but if they have the same mother, the Mother’s DNA sample can be included.

Mitochondrial Test

Mitochondrial DNA is only inherited from the Mother, so a Mitochondrial Test is the best DNA test to see if siblings have the same biological mother. The accuracy of the test strongly depends on the type of mitochondrial DNA sample. When two matching persons have a rare type of Mitochondrial DNA, then they are more likely to be siblings versus two individuals who match with a common type of mitochondrial DNA. The probability of two siblings being related is calculated after the type of DNA is established in the DNA test.

Sibling Full Test

If a man and a woman want to be tested to establish a genetic tie to the same father, then they will need to do a full sibling DNA test. This test is around 90% accurate, and is analyzed to see the amount of DNA shared between the siblings. Accuracy can be drastically increased with DNA from other siblings or the mother.

Where Can You Get DNA Testing for Siblings?

A DNA test for siblings is easy and painless. A DNA tech will collect a DNA sample by swabbing a small sample of the inside of each person’s cheek. After collection, the sample is submitted to a DNA testing lab and/or DNA testing doctor.

DNA Testing for Siblings can be performed at DNA testing centers. It is important to make sure that you choose a testing center that will provide confidentiality of information and of the DNA samples you provide.