the fact of involving sexual activity between people who are closely related and not legally allowed to marry

It’s a tale of Gothic incestuousness based on a novel by an Atlanta author. 这是一个哥特式乱伦故事，改编自一名亚特兰大作家的小说。

the incestuousness of their relationship 他们之间的乱伦关系

the quality of involving only a close or limited group of people, who do not communicate or do business with people outside the group

People are tired of the revolving-door incestuousness of Washington and Wall Street. 人们厌倦了华盛顿和华尔街的旋转门式的小集团勾结和利益交换。

Political incestuousness is routine at all levels. 政治乱伦在各个层面都是家常便饭。