Elissa Shevinsky can pinpoint the moment when she felt that she no longer belonged.
She was at a friend’s house last Sept. 8, watching the live stream of the TechCrunch Disrupt hackathon on her laptop and iPhone. Entrepreneurs were showing off their products, and two young Australian men, David Boulton and Jethro Batts, stood behind the podium to give their presentation. “Titstare is an app where you take photos of yourself staring at tits,” Mr. Boulton began, as photographs of women’s chests on a cellphone flashed on the screen behind him.
After some banter, Mr. Batts concluded, “This is the breast hack ever.”
The crowd — overwhelmingly young, white, hoodie-wearing men — guffawed. Something in Ms. Shevinsky’s mind clicked. If ever there was proof that the tech industry needed more women, she thought, this was it.
Tech executives often fault schools, parents or society in general for failing to encourage girls to pursue computer science. But something else is at play in the industry: Among the women who join the field, 56 percent leave by midcareer, a startling attrition rate that is double that for men, according to research from the Harvard Business School.
A culprit, many people in the field say, is a sexist, alpha-male culture that can make women and other people who don’t fit the mold feel unwelcome, demeaned or even endangered.