Using DNA to determine if siblings have the same father

A DNA sibling test is used to compare the DNA of an individual to that of another person to determine whether they are related biologically as siblings or not. Generally, the sibling test is used to determine paternity, that is whether a person is or isn’t a father of the siblings in question.

When this test is used?

• This test is often used when the father is not willing to take a paternity test.
• In cases where the father is deceased or not present.

What are the uses of a sibling DNA test?

• This test can be used in legal terms to obtain social security survival benefits.
• The sibling DNA test makes reconstructing your parents’ genomes easier and more complete and the DNA profiles for your ancestors.

There are 2 types of Sibling DNA Tests:

• Full Siblings vs. Half Siblings: In this test, the DNA from two different persons with the same biological mother is compared, to determine the chances of them having the same biological father. For this test, samples from the biological mother are also tested to increase the accuracy of the test.
• Half Siblings vs. Unrelated: In this test, the DNA of two different people with different biological mothers is compared, to determine the chances of them having the same biological father. For this test, the samples from both of the biological mothers are tested to increase the accuracy of the test.

Read more: Who should go for the genetic testing during pregnancy?

The conclusiveness of sibling DNA test:

It is to be noted that the final result of sibling DNA test is not as conclusive as a paternity test due to the fact that the percentage of DNA inherited by a child from both of its parents differs which, as a result, changes the no. of genetic markers found in DNA. These genetic markers are used to determine the parentage of an individual to the child of whether two individuals are biologically related or not. So the result ends up being less conclusive.