On the night of Sept. 19, 1961, Barney and Betty Hill were driving on a rural highway to their home in Portsmouth, New Hampshire. By all accounts, the Hills were an exemplary couple: he a postman, she a social worker, active in their community and in the civil rights movement. On an isolated road snaking through the White Mountains, the couple later recounted, they saw a bright object that appeared to be following their car. They arrived home around 5 a.m., unable to account for two hours of the night but feeling that something terrible had happened to them.

It took a while, but the Hills eventually remembered the life-altering event that befell them on that lonely stretch of highway: They’d been abducted by aliens.

The Hills’ claim was the first publicized account of alien abduction. Their story—which they told first to a psychiatrist, then in a book and TV movie—formed the template for countless abduction stories to follow. Details vary, but the typical alien abductee hews to the basic script of the Hills’ self-reported encounter: They are taken by otherworldly beings, subjected to various experiments, and returned, never to be the same.

Today, some 2.5% of the US population reports having some personal experience with alien abduction. (Coincidentally, the same percentage reports having voted illegally.) Studies by sober-minded, non-ufologist psychologists have identified two truths that apply to most people in this unique cohort, including the Hills. They’re not lying, at least not consciously—most people who say they were kidnapped by aliens really believe they were kidnapped by aliens, even if the evidence doesn’t support their claim. And they’re not crazy, at least not in the way we think of when we talk about crazy people, though they tend to differ from the rest of the population on some key psychological traits.

These self-reported abductees are participants in a cultural myth that can be directly traced to Barney and Betty Hill, whose own story came about only after aliens started kidnapping people in movie and TV plot lines in the late 1950s. Reports of flying saucers surfaced in the late 1940s; aliens were fixtures of science fiction by the dawn of the 20th century. But the trope of real people actually being spirited away by such beings is only as old as the Hills.

“We in the late 20th century may well be in the exciting position of being able to observe and study a myth in the process of being created,” wrote English professor Terry Matheson in his 1998 book Alien Abductions: Creating a Modern Phenomenon. An annual meeting of alien abductees convenes in Rhode Island; support groups for abductees—or “experiencers,” as many prefer to be called—thrive online. In honor of World UFO Day (July 2), it’s worth taking a look back at the point where all their stories began.