Originally Posted by Chewy
How are Black Bolt and Medusa related? I have no idea. I assume the Inhuman family tree will include more families anyway, to avoid all instances of incest
All of the Inhuman royal family refer to each other as "cousins" except brothers Black Bolt & Maximus and sisters Medusa & Crystal. I can't remember if they are all really first cousins or that is just a traditional form of address. They seem to follow the mode of European royal families, which were all interrelated and allowed for marriage between cousins, which only relatively recently became controversial.