The following table summarizes the average percent DNA shared for different types of relationships according to our simulations. You may notice that several relationships share the same average percent DNA; this can account for a predicted relationship of aunt/niece for a pair of half sisters.
|Relationship||Average % DNA Shared||Range|
|Parent / Child
|50%||Varies by specific relationship|
|Grandparent / Grandchild
Aunt / Uncle
Niece / Nephew
|25%||Varies by specific relationship|
|1st Cousin||12.5%||7.31% - 13.8%|
|1st Cousin once removed||6.25%||3.3% - 8.51%|
|2nd Cousin||3.13%||2.85% - 5.04%|
|2nd Cousin once removed||1.5%||0.57% - 2.54%|
|3rd Cousin||0.78%||0.3% - 2.0%|
|4th Cousin||0.20%||0.07% - 0.5%|
To learn more, visit the International Society of Genetic Genealogy website.