| Sibling DNA testing is designed to | | | | true biological siblings. For instance, |
| determine sibling genetic relationships. | | | | a DNA index of less than 1.00 indicates |
| Such tests establish the statistical | | | | non-relatedness, whereas a DNA index of |
| probability of whether the siblings | | | | greater than 1.00 indicates that the two |
| share the same two parents. A DNA | | | | tested individuals are more likely to be |
| sibling test can be performed to analyze | | | | true biological siblings. |
| the relationship of biological siblings | | | | A half-sibling DNA index can also be |
| by collecting samples from both | | | | obtained to determine whether the |
| siblings; however, including one common | | | | siblings share only one common parent, |
| parent increases the accuracy of this | | | | versus two common parents. The ratio of |
| type of analysis, and is highly | | | | the half DNA index versus the full DNA |
| recommended. | | | | index establishes whether the two |
| While conducting sibling DNA testing, | | | | individuals share one parent or two |
| the DNA laboratory determines the | | | | parents. DNA testing can also help |
| genetic profile of the alleged siblings | | | | determine if twin siblings are fraternal |
| and, based on the type of genetic | | | | or identical. For instance, if the DNA |
| material inherited by each sibling, a | | | | profiles of the twins are different then |
| DNA index is determined. Based on the | | | | the siblings are considered fraternal; |
| results of the DNA index, the sibling | | | | however, if the profiles are identical |
| relationship is established and a higher | | | | then a probability of being identical |
| value DNA index indicates a greater | | | | twins is calculated. |
| likelihood that the two individuals are | | | | |