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How Is Siblingship
Determined? Siblingship DNA Test will give you a siblingship DNA index. When the index is below 1.00, this indicates that the siblings are not related. If the siblingship DNA index is greater than 1.00, this indicates that the two tested individuals are more likely to be true biological siblings. The higher the value of the siblingship DNA index, the greater the likelihood that the two individuals are true biological siblings. |
| Half
Siblingship vs. Full Siblingship? To analyze the possibility that the siblings share only one common parent versus two common parents (mother and father), a half siblingship DNA index is obtained. The ratio of the half siblingship DNA index versus the full siblingship DNA index would provide you with an idea of whether the two individuals are more likely to share only one common parent (e.g. mother only) or two common parents (mother and alleged father). Half Siblingship: Sibling 1 and Sibling 2 do not share the same mother and they want to find out if they share the same biological father—in this situation, a half siblingship DNA test is performed. Full Siblingship: Sibling 1 and Sibling 2 share the same biological mother but are unsure if they share the same biological father—in this situation, a full siblingship DNA test is performed. |
| How
Accurate Are The Results? Including one common parent greatly increases the accuracy of this type of analysis and is recommended if at all possible. If this is not possible, disclosing that siblings share a common mother or father can also lead to more meaningful results. |
| Who
needs to be tested? At a minimum, both assumed siblings must provide a sample. We also recommend that one or more of the parents, such as the mother, provide a sample for analysis. If the parents are not available, samples from other "known" siblings are also recommended. |
| Can
twins that are born at the same time have different fathers?
In some cases, fraternal twins can actually be half-siblings, with different fathers, even though they are born at the same time. DNA testing can help to determine whether fraternal twins have the same or different fathers. |