"Moving into the post-war era and the 1960’s, software engineering was considered “women’s work” because it was thought of as clerical. Hardware was the difficult job, i.e. “for men”. Cosmopolitan famously ran a 1967 issue about “The Computer Girls,” with Admiral Hopper saying women are “naturals” at computer programming. (By “naturals” Hopper wasn’t referring to biology, it should be noted, but to the responsibilities women were socialized in, such as planning a dinner and having everything be ready at the appropriate time.)
Starting in the late 1960’s, men realized programming was actually really hard, and thus, prestigious. That meant it was lucrative and valuable, and (some) men didn’t want women enjoying all the benefits of that. As researcher and historian Nathan Ensmenger helped reveal, professional organizations, smear marketing and ad campaigns were created that discouraged the hiring of women into computer science and programming roles. Meanwhile, aptitude tests were made (by men) that favored men in their evaluation steps, and the answers to those tests were circulated across male-only groups like fraternities. (Worth noting: women being shamed into or out of things via advertising has tremendous historical precedent.)"