Robert De Niro, twenty years after his father’s passing, is honoring him with a documentary that shows Robert De Niro Sr.’s genius as an artist and struggle with being an openly gay man in the 70s.

Robert De Niro Opens Up About Gay Dad

De Niro shared that it was a sense of responsibility that inspired him to catalogue his father’s life – though initially he only intended the project to be for his children and future grandchildren. “I felt I had to. I felt obligated. It was my responsibility to make a documentary about him,” De Niro told Out magazine. “It was not intended to be on HBO. It was just something I wanted to do.”

When he was just three years old, De Niro’s parents split up, which didn’t make it easy for him to bond with his father. Still, according to the Academy Award winner, there was an undeniable connection between them. “We were not the type of father and son who played baseball together, as you can surmise. But we had a connection,” De Niro revealed.

“My father wasn’t a bad father, or absent; he was absent in some ways,” De Niro added. “He was very loving. He adored me… as I do my kids.”

Though he was an out gay man while working as a struggling artist in New York City, De Niro Sr. still struggled with his sexuality. It was a part of him that he didn’t discuss with his son. De Niro’s mother also declined to offer him insight on this aspect of his father’s life. In his mature age, De Niro now looks back and wishes he could have had those talks with his dad.

“Yeah, he probably was [conflicted about his sexuality], being from that generation, especially from a small town upstate. I was not aware, much, of it,” admitted the actor. “I wish we had spoken about it much more. My mother didn’t want to talk about things in general, and you’re not interested when you’re a certain age.”

Throughout his career in Hollywood, De Niro has never played a gay character, but the actor maintains that that wasn’t a conscious choice – such roles just weren't offered to him. “They weren’t offered to me,” he said. “If they had been offered to me by a good director, that’s something I would have considered.”

Remembering the Artist: Robert De Niro Sr. premieres on HBO June 9.