Your Results
On page 2 of your test report, you will find a chart displaying the DNA profiles for each person tested. The DNA profile chart may look something like this:
| DNA Locus | Putative Sibling 1 | Putative Sibling 2 | Sibling Index (Full) |
Sibling Index (Half) |
| D8S1179 | 13,14 | 14 | 1.32 | 1.57 |
| D21S11 | 28,30 | 28,30 | 4.25 | 1.72 |
At the bottom of the table, you will see a Combined Full-Sibship Index and a Half-Sibship Index.
Combined Sibship Index
The Combined Sibship Index ("sibship index") is calculated by multiplying the the sibling index values for each DNA locus, and it is the final result of a DNA Sibling Test. The sibship index represents how many times more likely it is that the tested individuals are full-/half-siblings than not related.
| Sibship Index | Explanation |
| 10 | The individuals are 10x more likely to be true siblings than not siblings. |
| 100 | The individuals are 100x more likely to be true siblings than not siblings. |
| 0.01 | The individuals are 100x more likely not to be true siblings than siblings (1/0.01 = 100). |
In general, a larger sibship index (>1.0) corresponds to a higher likelihood of relationship. The higher that the sibship index is above 1.0, the higher the likelihood that the two individuals are related as siblings.
Likewise, a smaller sibship index (<1.0) corresponds to a lower likelihood of relationship. The lower that the sibship index is below 1.0, the lower the likelihood that the two individuals are related as siblings.
Recommended Interpretation of the Combined Sibship Index (Full/Half)
| Sibship Index | Interpretation |
| Greater than 10 | The genetic evidence is supportive of relationship. |
| 0.1 to 10 | The genetic evidence is inconclusive of relationship. |
| Less than 0.1 | The genetic evidence is not supportive of relationship. |
Are we half or full siblings?
To determine whether it is more likely that two individuals are full or half siblings, go to the second page of your DNA results report. Under the table, you will see two indices: Full Sibling Index and the Half Sibling Index.
If the Full Sibship Index is greater than the Half Sibship Index, then the individuals are more likely to be full siblings. Likewise, if the Half Sibship Index is greater than the Full Sibship Index, then the individuals are more likely to be half siblings.
To calculate how many times more likely one type of relationship is compared to the other (full vs. half), take the larger number and divide it by the smaller number.
In this example, if a sibling pair has a Full Sibship Index of 100 and a Half Sibship Index of 2, then they are 50 times more likely to be full siblings than half siblings.
Similarly, if a sibling pair has a Full Sibship Index of 1.5 and a Half Sibship Index of 20, then they are 13.33 times more likely to be half siblings than full siblings (20 ÷ 1.5 = 13.33).