Adelphogamy 

Adelphogamy means marriage between biological brothers and sisters.

they practise adelphogamy in Alabama

Adelphogamy by Bobbystrurrew July 20, 2023

adelphogamist 

An adelphogamist is someone who promotes romantic relationships between siblings

she's an adelphogamist

adelphogamist by Bobbystrurrew July 20, 2023

adelphogamize 

to adelphogamize is to promote adelphogamy, i.e. romantic relationships between siblings

they adelphogamized the Game of Thrones series

adelphogamize by Bobbystrurrew July 20, 2023

adelphogamism

adelphogamism is a genre of entertainment wherein adelphogamy, i.e. romance between siblings is mainstream

They're into adelphogamism

adelphogamism by Bobbystrurrew July 20, 2023