Like most based-on-a-true-story biographical films, Angela Robinson’s Professor Marston and the Wonder Women is only loosely connected to actual events. Psychology professor William Moulton Marston (played by Luke Evans in the film) did create the comic book character Wonder Woman, and he did live in a polyamorous relationship with his wife Elizabeth Marston (Rebecca Hall) and their grad student Olive Byrne (Bella Heathcote). Everything else in the movie, though, is up for grabs.

Robinson frames her film around the explicit war against Marston’s life and work. But in spite of complaints about the bondage in the Wonder Woman comics, Marston was never seriously threatened with being fired from the title he created. The comics sold too well, and he was too skilled at defending his work. In spite of the sultry lie detector scenes in the film, the lie detector Marston created never worked, and certainly wasn’t instrumental in getting William, Elizabeth, and Olive to declare their feelings for each other. So far as anyone knows, no neighbor ever wandered into the Marston household and found Marston, Elizabeth, and Olive having kinky costumed sex. William and Elizabeth didn’t subsequently split up with Olive, even temporarily. And as the photos over the closing credits prove, Elizabeth, Olive, and William did not look anything like glamorous movie stars.

But the movie depicts one important thing accurately: Elizabeth and Olive were bisexual. They didn’t just have separate sexual relationships with William. They had a sexual relationship with each other.

This doesn’t seem like it should be a controversial point. As the film notes, Elizabeth and Olive named their children after each other. After William died in 1947, the two women lived together for almost 40 years.

And there’s substantial evidence that the Marstons were aware of lesbian relationships and approved of them. Marston wrote extensively about female-on-female attraction in his scholarly work, going so far as to discuss the mechanics of tribadism and female oral sex. He presented lesbian sex as normal and healthy, and even suggested that half of all women were lesbians. Olive helped him research sorority initiation rituals; they concluded that the rituals were sites of intense same-sex eroticism. In one passage in his academic work, Marston describes two women making love in front of him. It isn’t difficult to figure out who those women were.

And this isn’t even getting into Marston’s erotic novel about Julius Caesar in which he describes lesbianism as “perfect,” nor the Wonder Woman comics, in which women tie each other up, spank each other, and dress up as deer in order to mime eating one another. Marston was an enthusiastic lesbophiliac who lived with two women in a polyamorous relationship. People have to be really committed to not seeing the obvious to not see the obvious. Yet, despite all of this, scholars and fans have still been remarkably reluctant to acknowledge that Elizabeth and Olive were lovers.

The Marston family’s polyamory was probably first discussed publicly by Les Daniels in his Complete History of Wonder Woman in 2004. Daniels acknowledged that Marston had children with both Elizabeth and Olive, but did not discuss Elizabeth and Olive’s relationship. That elision has continued, to some extent, to the present day. Jill Lepore’s recent wildly popular Marston biography, The Secret History of Wonder Woman, includes accounts of naked feminist New Age sex parties, but is oddly coy about acknowledging Elizabeth and Olive’s bisexuality. At times, Lepore broadly hints, as when she points out that Elizabeth was a lifelong fan of Sappho’s poetry. And then at other times, Lepore seems to deny the lesbian relationship, as when she includes a (poorly sourced) anecdote suggesting that William threatened to leave Elizabeth if she didn’t accept Olive into their marriage.

Why have people been so reticent about acknowledging that Elizabeth and Olive were lovers, when Elizabeth and Olive were obviously lovers? In 1990’s The Epistemology of the Close, Eve Sedgwick argues that the refusal to admit that figures in the past were gay is part of the way the dominant culture represses and denies homosexuality. Sedgwick says scholarship and history respond to gay people in the past by commanding, “Don’t ask. Or, less laconically: You shouldn’t know.” Because of stigma, queer people had to hide — and then historians use their lack of clear visibility as false proof that they didn’t exist. Heterosexuality is the assumed default. Sedgwick notes drily that without ironclad proof “such as sperm taken from the body of another man or a nude photograph with another woman… the author may be assumed to have been ardently and exclusively heterosexual.” Even two women living together for four decades, with evidence that they shared the same bed, isn’t enough to say for sure.

The assumption behind this sort of high barrier to belief is that there’s something shameful about same-sex attraction. In the case of the Marstons, bisexuality is somehow even more verboten than polyamory. That attitude isn’t just homophobic, it’s also a betrayal of Marston’s entire life’s work. In his scholarly writing and his comics, Marston insistently, deliberately portrayed lesbianism as normal and good. He encouraged children to see diverse erotic possibilities as fun, enjoyable, and exciting, not shameful or dangerous. And he insisted that women were powerful, loving, and in control of their own desires.

“Olive and Elizabeth were kind of hidden by history. I thought that was very much a reflection of their times.” —Director Angela Robinson discusses what she intended with Professor Marston

If Olive and Elizabeth weren’t lovers, the Wonder Woman comics turn into some weird stifled fantasy, a vision of eroticized lesbian love which existed only in Marston’s fantasies. But it seems much clearer that the early comics’ playful eroticism was meant as a love letter to the woman Marston cared about. It was an effort to imagine, and to bring about, a world in which they wouldn’t have to hide.

Professor Marston and the Wonder Women is really more about Elizabeth and Olive’s love than it is about Marston, and that’s a choice Marston himself would have strongly approved of. We don’t know that Marston lost his job because of his polyamory, as the movie claims, nor is there evidence that the family’s neighbors shunned them. But the fact that Elizabeth and Olive’s relationship has been denied for so long suggests the effect homophobia and the need for secrecy had on their lives. Director Angela Robinson, a lesbian herself, opens the closet door, and presents the love of William, Olive, and Elizabeth, not as shameful, but as courageous and beautiful. Inevitably, the film gets a lot wrong, but it does get that much right.