Responses
You forgot the 'been away or lost for several years' reunion, the distant cousin, and 'replacement child'
Honestly I'm so desensitized if the art is decent, I'll read it so long as they're not blood related or minor x much older adult... even the "legal lolis" are pretty questionable. If they look, sound, and act like children--FBI OPEN UP!

Not important but this is how I decide which "incest" relationship in fiction I can swallow :
Blood siblings (including step siblings with one shared parent) = NOPE
Step siblings from different parents (not blood related at all) :
a) if they grow up together, or has at least once view each other as siblings = NOPE
b) if they grow up together but has terrible relationship that they won't even consider the other as family = Tolerable
c) if they become siblings as adults (parents remarry late) and they just roll with the arrangement = Tolerable
d) if they become siblings as adults but at least one of them so excited of having/thinking the other as blood sibling = NOPE
Adopted children :
a) Grow up together and raised as siblings = NOPE
b) The adopted one is adopted so late in their growth (maybe late teens after their guardians died) and have little to no familial bond with the other siblings = Tolerable