Knowing who is related too closely to you can be a problem on a small island, the comment was possibly referencing the Icelandic dating-app that tracks if you share a grandparent with someone you meet in a bar[1]; a feature the app itself calls a "Sifjaspellsspillir", or "Incest Spoiler".
Interestingly the article mentions that this is a problem precicely because of the Icelandic naming scheme:
> Neither patronymic or matronymic, instead each person's father's first name becomes the child's last name. Each new generation has a completely different name to the name of the generation that preceded it. Cousins, aunts, uncles, nieces, nephews -- all could have very different names.
Interestingly the article mentions that this is a problem precicely because of the Icelandic naming scheme:
> Neither patronymic or matronymic, instead each person's father's first name becomes the child's last name. Each new generation has a completely different name to the name of the generation that preceded it. Cousins, aunts, uncles, nieces, nephews -- all could have very different names.
[1] https://www.wired.co.uk/article/iceland-incest-app