AI-Generated Books Capture 63% of Amazon Religion Titles

AI books dominate Amazon categories

Amazon's self-publishing marketplace has become saturated with AI-generated content, according to two recent studies that quantify the scale of machine-written books now competing with human authors.

An Originality.AI report found that 1,272 of 2,000 religion titles published on Amazon in the past year—63%—were flagged as likely written by large language models. A separate Stony Brook University study examined 14,419 self-published genre-fiction books sold between 2023 and 2026, finding that 2,880 titles (20%) contained substantial AI text, defined as more than 25% machine-generated prose. Nearly 1,000 novels were more than 90% AI-generated.

The financial impact on human authors is measurable. While the number of books with observed quarterly sales increased 19.2-fold over three years, revenue grew only 8.9-fold—indicating declining revenue per book as AI titles flood the market.

Why it matters

The proliferation of AI-generated books creates a crowding-out effect that reduces discoverability and sales for human authors, particularly those without established reputations. As algorithmic recommendation systems prioritize books based on clicks and purchases, the sheer volume of AI titles increases their likelihood of appearing in search results and related-book listings, creating a feedback loop that further marginalizes human-written work.

The algorithmic squeeze

"If there is an author who is not a very big name, very famous, and they have completely written a book with their sweat and tears, now that book might not even show in the related books listing because there is so many AI-generated books that are surfacing based on the keyword and the search terms associated with them," Tuhin Chakrabarty, assistant professor of computer science at Stony Brook University and study coauthor, explained.

Paramveer Dhillon, associate professor of information at the University of Michigan and coauthor, noted that even some higher-quality AI books contribute to the problem: "The crowding-out effect generated by these books—most of which are low quality, but some of which are still good enough that they lead to higher ranks—due to this increased competition, they're likely to get squeezed, and their revenues are reduced."

Amazon requires self-published authors to disclose AI use and limits uploads to three titles per day. The company stated it takes "proactive and reactive measures to prevent, detect, and remove content that violates" its guidelines.

Retailers navigate murky waters

Booksellers face difficult decisions about AI-generated content. Barnes & Noble CEO James Daunt said the retailer would not ban AI books outright if properly labeled, but acknowledged the complexity: Should stores refuse books that are 25% AI-generated? 50%? The line-drawing exercise, he noted, "would take a days-long conference to explore."

The researchers predict a bifurcated market emerging—one segment catering to readers comfortable with formulaic AI content, another demanding literary quality that current AI cannot achieve. Human authors will need to choose which market they serve.

These details were first reported by Fortune, based on the unpublished Stony Brook University study and the Originality.AI report.