What is the relatedness (r) between two grandchildren of a woman, with each grandfather being a different partner?

To determine the relatedness (r) between two grandchildren from the same grandmother but different grandfathers, we can analyze the genetic contributions from each grandparent.

Each grandchild shares one-quarter (0.25) of their DNA with their grandmother, as they inherit half of their genetic information from their parents. Each grandchild also has a grandfather, but since they have different fathers, they do not share any genetic material from their respective grandfathers.

The two grandchildren share only their grandmother as a common ancestor. The relatedness (r) can be calculated by taking the shared genetic contribution from the grandmother into account:

1. Each grandchild inherits 0.25 from their grandmother.
2. The overall relatedness through the grandmother to the two grandchildren is therefore calculated as follows:
   • They share 0.25 (common grandparent) x 0.5 (one-half of her contribution as they are grandchildren) = 0.125 (or 12.5%).

Since this calculation indicates that the correct answer should actually be 0.125, it's noteworthy that the provided answer of 0.0625 does not reflect the correct relationship in this context. The accurate relatedness should represent the cumulative contribution from the shared