Robert De Niro showed "Remembering the Artist: Robert De Niro Sr." at the Aspen Ideas Festival last week. The short documentary film chronicles his late father's struggles in his career as an abstract painter, and touches on the emotional turmoil the elder De Niro experienced as he grappled with his sexuality.

In an interview with Katie Couric, the Academy Award-winning actor discussed what he learned from his father's journals and poems that were never discussed before his father's death.

"He was very private so he wouldn't go into that with me," De Niro said of his father's homosexuality. "I don't really know much about that side of my father."

When Couric asked if he had an idea that his father was gay, the 70-year-old stated he had "some inkling," and that his mother made "some inferences about it."

"You kind of like, knew but didn't know," he said.

The topic was something that De Niro Sr. battled with himself, as evidenced by his journal entries.

"If God doesn't want me to be a homosexual (about which I have so much guilt) he will find a woman whom I will love and who will love me or at least create an interest in me in women as sexual partners," he wrote.

"The pills don't help or the prayers either. God! God! God!"

The artist also related his creative work to the gay experience of his time.

"Being a painter is an affliction. Like being a homosexual," he explained.

"One has to have the strength to continue working without the recognition either before or after death just as one had to have the strength to accept life alone without the thought of romantic attachment."

De Niro Sr. passed away in 1993 at the age of 71 from prostate cancer.

His son said he wished he created the documentary while he was still alive.

"Obviously, I realize now that it was hard for him," De Niro told Couric.