People look at successful entrepreneurs such as Mark Zuckerberg, Elon Musk, and Travis Kalanick and wonder if there’s a certain formula that has led to the success of these billion-dollar company founders. While some may say that it may have something to do with their attitude, a new research shows that part of their success may be due to where they went to school.

According to CNBC, cloud accounting software company Sage has compiled data from TechCrunch, Crunchbase, CB Insights, and VB Profiles and found that some institutions have produced graduates who founded “unicorn” companies. In this case, a unicorn is defined as a private start-up worth in excess of $1 billion.

Based on the study, it was revealed that Stanford University counts 51 unicorn founders as alumni, which include Allen Blue, Eric Ly, and Konstantin Guericke of LinkedIn; Avery Wang and Dhiraj Mukherjee of Shazam; and Brian Acton of WhatsApp.

The next institution with the most unicorn company founders is Harvard, with 37 unicorn alumni including Facebook’s Zuckerberg, Dustin Moskovitz, Andrew McCollum, Chris Hughes and Eduardo Saverin. Jason Kilar of Hulu, Marc Pincus of Zinga, and Nathan Blecharczyk of Airbnb also came from Harvard.

The University of California has 18 unicorn founders, including Uber founder Kalanick, Nicholas Woodman of GoPro, and Logan Green of Lyft.

So why does Stanford have the most unicorn company founders among all the universities in the whole world? According to Independent, Stanford Easley, who teaches a course in technology entrepreneurship at the university’s School of Engineering, said that the entrepreneurial spirit started with the school’s founders.

“Stanford was created by people who came to the Western Frontier,” said Easley. “The settlers were community builders. They took risks by coming west and starting from scratch.”

It was reported that apart from the aforementioned Stanford alumni who went on to become unicorn company founders, subsequent alumni include the founders or co-founders of Yahoo!, Netflix, Paypal, Netflix, YouTube, and Mozilla Firefox, among others. Google founders Sergey Brin and Larry Page also graduated from Stanford, and it was said that one in 20 Google employees is a graduate of the prestigious university.

Raymond Braun, who is a graduate of Stanford and is now part of the marketing team of YouTube, explains why most graduates prefer to work at Google.

“There are a lot of similarities between the Stanford culture and the Google culture,” said Braun. “Stanford is always looking towards the future, and it pushes students to take an entrepreneurial attitude to their own education.”

For more, check out Jobs & Hire’s report about the Manhattan etiquette school that is attracting young professionals.