Loved the article.

I've long wondered about the math behind my buddy's nieces and nephews' genetic relatedness.
His brother and sister are married to another set of sister and brother. The younger pair met at the olders' engagement party. Aww.

So ten years into the marriages there are six kids - three from each couple. What is the relatedness between these sets of cousins? Is it 1/8 rather than the 1/16 we normally see in first cousins? All of the kids have a similar appearance, but the biggest resemblance is between two of the cousins rather than any of the siblings.