A new addition has joined the already impressive roster of feature-length documentaries this year. Three Identical Strangers tells the story of how identical triplet babies were placed by an adoption agency in three different homes in the New York area. The boys and their adoptive parents knew nothing of each other until one of them, Bobby, arrived at an upstate college and was greeted by many strangers who thought of him as an old friend. One person who recognized him figured out what was going on. Asking if he was adopted and if he was born in June 1961, he reasoned that Bobby’s double, named Eddie, must be his twin brother.

This was confirmed, and the boys had a touching reunion. The media picked up the story, and it went as viral as a story could back in the early 1980s. Then it turned even more incredible when someone else saw a photo of Eddie and Bobby in the paper and realized she knew another identical boy, David.

For much of the film, we witness how finding each other changed the boys’ lives. But we also hear everyone wondering how such a thing could have happened. Louise Wise, the adoption agency responsible for their placements, defended themselves saying that it would have been impossible to place three  children together.

Not that they tried. Instead of the separate adoptions being an administrative mistake or an error in judgment, we soon learn that (spoiler alert) this was part of a deliberate plan by psychologists. They were trying to find a way to compare the relative influence of nature vs. nurture  (genetic inheritance vs. childhood events and environment) in shaping personality. Though records are sealed away in Yale University’s Child Study Center, it appears they were especially interested in the relative effects of genes vs. environment on mental and emotional illness. The three families chosen for placement were from different socioeconomic groups, a factor of interest to the researchers.

The triplets and their families were outraged when they discovered this. They all felt that something had been stolen from them, and they were treated no better than “lab rats.” We soon discover that they were not the only adopted children who were treated this way. Though probably the only set of identical triplets, there were twins separated at birth who were studied as well, though we don’t know how many pairs were involved.

However lofty the scientific intentions of the experiments, all agreed that it was unethical to do this without the subjects’ knowledge. I can imagine the scientists would have argued that to have done so would have altered the “conditions” of the experiment. Some interviewed in the film felt a chilling similarity to Nazi era eugenics in the doctors’ willingness to put science above humane interests. Ironically, the psychiatrist in charge of the study, Dr. Peter Neubauer, was himself a Holocaust refugee.

Another bitter irony is that we don’t know what was learned from the study. The results weren’t published in any journals, and the raw data is still under seal at Yale—until the 2060s.