The clone is incest because even though she was a clone of Jean she still has the same genetic markup as her. Therefore though she wasn't technically his mother she is relative to him and shares 50% of the genes he does; making their relationship incestuous.
The royal family is inbreed. It has been stated in the comics that BlackBolt and Medusa were cousins. Anyways marvel will probably retcon this soon. Crystal also often referred to BlackBolt and Maximus as her Uncle. Though this was probably more of a writing mistake.
I forgot that it was StarHawk's adoptive sister. You're right it isn't genetically incestuous. Just down right creepy because they were raised as siblings.
Anyways I really do not want to derail this topic and turn it into a conversation about the instances of incest in marvel. My previous post was in no way serious and was intended to be read in a bitter sarcastic tone, as I am very angry and frustrated with marvel at the moment for ruining the inhumans and making Pietro and Wanda no longer Magneto's children.