Siblingship DNA Test

This DNA test calculates the statistical likelihood that siblings share the same two parents, one parent, or no parent at all. When siblingship is in question, the recommended method of analysis is to test their known parents. When the alleged parents are unavailable for testing, a DNA siblingship test can be performed. Including one common parent greatly increases the accuracy of this type of analysis and is recommended, if at all possible.

Siblingship test results are best related in terms of probability and can fall anywhere between 0% and 99.99%. The higher the percentage, the more likely the tested individuals are related, however, in some cases siblingship results may be inconclusive.

Two individuals who share both biological parents in common are called full siblings, whereas two individuals who share only one biological parent in common are called half siblings. On average, full siblings share 50% of their genes due to common inheritance, whereas half siblings share 25%.  There are 3 different types of statistical analyses that can be performed for DNA sibling tests, which are based on the particular parental relationship(s) in question:

Full Siblings vs. Unrelated.  In these sibling tests, the DNA of two individuals is compared to determine the likelihood that they have the same biological mother and father, versus being completely unrelated.

Full Siblings vs. Half Siblings In these sibling tests, the DNA of two individuals with the same biological mother is compared to determine the likelihood that they have the same biological father.  For these tests, we recommend that samples from the biological mother be tested. This addition greatly increases the conclusiveness of the test.

Half Siblings vs. Unrelated.  In these sibling tests, the DNA of two individuals with different biological mothers is compared to determine the likelihood that they have the same biological father.  For these tests, we recommend that samples from one—and preferably both—biological mothers be tested. This addition greatly increases the conclusiveness of the test.

It is important to understand that, unlike a traditional paternity test, it is not always possible to obtain a conclusive result in a DNA siblingship test. This is, in part, because the pattern of inheritance and degree of sharing of genetic markers between two siblings are not the same as that between a parent and child.  In a sibling DNA test, the degree of certainty that can be achieved depends upon who is available for testing as well as the specific type of sibling relationship being tested. As a general rule, the more genetic information available, the greater the chance the test will be conclusive.

Endeavor DNA offers a 2 business day turnaround on siblingship tests utilizing either buccal swabs or specimen collection cards (WhatmanTM FTA® or WhatmanTM 903) with rush testing options available. Endeavor DNA can also test a multitude of other sample types, but longer turnaround times may apply.

All Endeavor DNA siblingship tests utilize stringent, validated testing procedures and include up to 22 STR loci plus the gender identification marker amelogenin in order to achieve 100% accurate results.

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