If it talks like AI, and it walks like AI, it might just be AI.
An application to the startup accelerator Y Combinator includes several written prompts. Founders need to explain how they picked the idea, who their competitors are, and how they'll make money. Many techies have offloaded their writing skills to AI — and application data suggests it shows in their applications.
YC applications have grown by 60% in length over the past three years, according to partner Tyler Bosmeny. "I wonder what could explain that..." he wrote on X.
Pete Koomen, another YC partner, wrote on X that he noticed a difference. He thought: "Back in my day (one year ago) founders didn't talk like this."
The word "wedge" began to rise in prevalence in 2025, according to a graph Koomen shared. By the summer 2026 batch, the word was in about 20% of applications.
Em dashes took off a bit earlier, starting in 2023 and accelerating in 2024. By the summer 2025 batch, em dashes were used in over 50% of YC applications, according to the data.
Koomen pointed out that the spacing of the em dashes mattered. The use of em dashes with spaces around them (so spaced — exactly — like this) spiked in summer 2025. That's also when "wedge" spiked, Koomen said, and coincides with the launch of Anthropic's Opus 4.
The results aren't uniform. One of the suspected trademark words of AI-generated writing is "delve." Koomen found that it spiked in winter 2024 — but never appeared in more than 1.25% of applications.
Should I use AI in my Y Combinator application?
Y Combinator doesn't have specific guidance about AI use in its applications, unlike some companies like Anthropic. Its former and current leaders have shared some conflicting viewpoints.
CEO Garry Tan said he writes with AI during an appearance on the "Naval" podcast in July.
"I sure do," Tan said. "You caught me."
Tan said that you can "fix" when AI writes poorly. When one of the podcast hosts said that good writing was a product of good thinking, Tan countered that he was having "high-bandwidth conversations" with an AI model.
Paul Graham, YC's retired cofounder, has taken a more negative view. In May, he posted on X about the emails he received from founders, which were written in a "hard-hitting journalistic style."
These emails are written by AI, Graham wrote. He instantly moves on: "It feels like being lied to, and who would stand for that?"
Graham has also narrowed in on the word "delve." It's not that he dislikes the word, he wrote in 2024, but that it's a sign of ChatGPT use.
Still, YC seems invested in the future of AI-generated writing. There are at least two YC-backed startups that specialize in it.
