Like all great documentaries, Netflix’s “Tell Me Who I Am” focuses on a unique situation but makes it universal. The Oscar-potential film centers on twins Alex and Marcus Lewis. The 18-year-old Alex went into a six-week coma after an accident. When he awoke, he didn’t remember anything about his life, and didn’t recognize anyone — except his brother. So Marcus began filling him in, painting an upbeat picture of their youth.

The doc, from director Ed Perkins and producer Simon Chinn, challenged that picture. An outgrowth of the twins’ 2013 book of the same name, it taps into primal issues of trust, memory, family, cruelty, kindness and healing, and the secrets we hold, even from those to whom we are closest.

Marcus had filled in a few facts about their childhood with the book. But even when he started the film, he wasn’t ready to be completely open. His brother Alex said, “That five-year gestation period was not by design, but it was necessary to build the trust.” Alex had told the director, “I need my brother to give me everything so that I can move on.”

Because they’re English and reserved, and because humans sometimes have trouble opening up to those closest to them, “Marcus had no idea that’s how his twin felt,” says director Perkins. “It was a challenging position. So we tried to create a safe space so they could have conversations they’d never had.”

In the back of everyone’s mind was the question of what was unspoken. Chinn points out, “Marcus kept challenging Ed, ‘Why should I talk about this?’ Ed, to his credit, kept shifting responsibility back to Marcus saying ‘You don’t have to.’ ”

Marcus says, “It wasn’t until the movie came along that I realized I hadn’t really given Alex anything. In the book, it was all very general, a few facts. Alex wanted more. I had no intention of giving the speech that I give in the film, but it just came out. Ed facilitated that.”

Filming and editing were hard on the twins, but also affected the filmmakers. Director Perkins says: “You always feel an attachment to your subjects, but this was harder because we spent so many years getting to know these two. It’s the first time I’ve ever cried behind camera.”

Alex says the film provided “absolute closure,” in ways that their book didn’t. Marcus says, “I feel free,” after withholding details for decades. “We hope that it starts conversations, where other people can talk about their experiences.”

When they first discussed the film, Marcus turned to producer Chinn and said, “There are years of hurt here. So you have to look me in the eyes and tell me you’re gonna make something amazing.” In “Tell Me,” that promise was fulfilled.