GPT-3, the language model powering the free version of ChatGPT, has been shown to have been trained on the Omegeverse, a subgenre of speculative erotic fiction.

WIRED reported that fanfiction writers discovered that writing assistant app Sudowrite, which uses 'several variants' of OpenAI's GPT-3.5, was generating text describing a highly specific sexual act called 'knotting', an Omegaverse term in which a male 'Alpha's' penis locks itself inside a vagina during sex. 

The sexual act was also described by ChatGPT, according to a test conducted by Futurism. 

The findings prompted complaints from Omegaverse authors about the ethics of using their writing to train OpenAI's large language models, without their knowledge or permission. 

It also highlighted concerns about the safety of ChatGPT.