Tuna grew up in Evansville, Indiana. Both of her parents were medical doctors. In high school, she was valedictorian, served as student council president, and founded her school’s Amnesty International chapter. She studied political science at Yale University, where she received a BA degree in 2008.
While pursuing her undergraduate studies, Tuna wrote extensively for Yale Daily News. She subsequently contributed to the Evansville Courier & Press, interned at the Minneapolis Star Tribune and, between 2008 and 2011, was a reporter for The Wall Street Journal, where she covered the California economy, the real-estate market, and the higher-education system.
Tuna started dating Dustin Moskovitz, the co-founder of Facebook and Asana, around 2009. In December 2010, Tuna and Moskovitz signed the Giving Pledge, becoming the youngest couple ever to do so. To fulfill that commitment, they established the foundation Good Ventures, of which Tuna became its president. At around that time, while preparing to transition from journalism to philanthropy, Tuna read Peter Singer's The Life You Can Save, which introduced her "to the idea of not just trying to do some good with your giving, but doing as much good as you can." It was also from that book that Tuna first learned about GiveWell. Shortly thereafter, she and Moskovitz met Holden Karnofsky, who was then GiveWell's co-executive director. Tuna was impressed by GiveWell's commitment to both transparency and cause neutrality, and a collaboration between Good Ventures and GiveWell ensued. In April 2011, Tuna joined GiveWell's board of directors; in December that year, Good Ventures gave substantial grants to GiveWell's top-rated organizations; and in June 2012, Karnofsky announced that GiveWell and Good Ventures planned to "act as a single team", which resulted in the creation of GiveWell Labs and, in August 2014, of the Open Philanthropy Project.
Under Tuna's leadership, Good Ventures has, as of August 2022, granted over $1.7 billion to organizations working in global health and development, farmed animal welfare, global catastrophic risks, and other cause areas....