23andMe/Autosomal DNA testing of family members
Below are actual graphs of the comparisons between different members of my family who have tested their autosomal DNA at 23andMe. The true relationship is documented.
I want you to notice that the most DNA is shared between a parent and a child, 50%, as well as full siblings- about 50%. As the relationship widens, the amount of identical DNA plummets to almost undetectable amounts beyond a third cousin relationship.
You can use these graphs to help figure out relationships between close family members of unknown origins. If you have specific questions about a particular graph, such as the path of inheritance or ethnicity of the involved individuals, please contact me.
Parents and children
Third cousins, once removed
Fourth Cousins, once removed