I first heard the word Koekoeksgraad last week and liked it so much that I wanted to share it with you. Koekoeksgraad means “degree of cuckoos,” the degree of non-paternity events per generation.
I first heard the term in a presentation by forensic DNA expert Maarten Larmuseau, in a Youtube recording of his presentation about using Y-chromosomes to calculate the percentage of “cuckoos,” children whose biological father doesn’t match the documented line.
Their research found that both historically and today the degree of non-paternity events in the Netherlands and Flanders is about 0.9%, way lower than the 10% that is sometimes cited in media.
What I found interesting is that the rate didn’t change over time. Testing modern fathers and sons found the same koekoeksgraad of 0.9% as the historic rate, calculated using Y-DNA. It is remarkable that modern options like birth control and divorce haven’t had more of an impact.
It certainly is reassuring that we can be 99% sure that our paper genealogy is accurate 🙂
For those of you who understand Dutch, here is the video of the presentation: