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Sibling DNA Testing

DNA testing is a great way to find out the true biological parents of siblings.
Saptakee Sengupta Apr 17, 2019
Sibling DNA testing in a scientific technique to detect the biological parents of two siblings. Participation of minimum two siblings is required to carry out the test. Today, these tests are gaining prominence in determining true parents of children.
You will come across a plenty of legal issues associated with the process of identifying the genetic background of a child through DNA paternity testing and sibling DNA analysis.
Identity of the child, normally, remains undisclosed in cases of infidelity, rape, and forceful conception. Finally, when the problem crops up, couples resort to this technique, to find out the ultimate solution.

Testing Types

Determining siblingship is a legal procedure and requires submission of proof after the test has been performed. After successful completion of the test, you have to submit the notarized documents of your identity proof, that includes, birth certificate, driver's license or any other identity proof.
The existing relationship is established when close identity is proved through the results. There are two methods that can be used to carry out this test.

Full Sibling DNA Testing

In this case, the test is performed to find out if two siblings share two biological parents. The results are meant to prove that the mother and the father of both the siblings is same.
Thus, the DNA sample of both the siblings is compared with both the parents. This way one gets confirmation of their biological status.

Half Sibling DNA Testing

This test is performed to find out the common biological mother or father. The alleged siblings perform the DNA test to find out if they share single biological parent. This is the case when two siblings do not have the same biological mother while the father is common to both. The test can go in the other way as well.

Testing Methods

Testing sibling DNA is a complicated method. Brother/sister, brother/brother, and sister/sister tests differ from each other, although the initial steps are the same. Cousin DNA testing is done only for certain specific purposes that could be personal or legal.
In terms of genetics, the samples of first cousins are collected and then either less than 20% or more than 80% similarity is found out. However, not all organizations perform this test. Mentioned here are the methods of DNA testing of siblings.

X/Y-STR Testing

In this method, the Short Tandem Repeats (STR) of the DNA are examined. These repeats act as markers of DNA in an individual. Both males and females can take up this test. 17 STR markers of the X-chromosome are arranged in the test row and the rest two DNA samples of the siblings are compared with this marker.
It is then compared with the STR markers in the X chromosome of the siblings. The results are calculated on the basis of probability of the closest match. The same method applies for Y STR testing. This technique is believed to be extremely accurate.

Autosomal Testing

Both males and females can take up autosomal DNA testing. This is a great way to prove relationships between siblings and extended families. The presence of CODIS marker forms the basis of this test. There are 23 pairs of chromosomes, out of which, 22 are autosomal and one pair forms the sex chromosome.
In single panel test, 15 autosomal markers are compared with 13 CODIS while in a double panel test, 24 autosomal markers are compared with the same CODIS markers. Maximum match indicates existence of a relationship.
To perform this genealogical DNA test, the sample is extracted from the inner lining of the cheek also known as buccal cavity. It is then stored and processed to extract the DNA.
Today, test kits are available in medical stores and hospitals to perform sibling testing at home. A few good organizations also offer free DNA. Make sure you get it done from a reputed and authentic center for accurate results.