All blue-eyed people have a single ancestor in common

Ten years ago on HN:

https://news.ycombinator.com/item?id=111628

Also, somewhat more recently:

https://news.ycombinator.com/item?id=15194123

https://news.ycombinator.com/item?id=14309525

None have much discussion, but there were fewer people here ten years ago, so perhaps the five comments that are there are more valuable.

Then again, maybe not.