Credit: Courtesy of The Estate of Whitney E. Houston

Whitney, the new documentary about Whitney Houston which debuted at the Cannes Film Festival Wednesday, drops a major bombshell about the late icon: She was allegedly sexually abused as a child by Dee Dee Warwick, Houston’s cousin and the sister of soul singer Dionne Warwick.

This revelation comes at the end of the film (directed by award-winning Scottish filmmaker Kevin Macdonald) when Houston’s former longtime assistant, Mary Jones, alleges that the singer told her that she was molested as a young child by her cousin Dee Dee, the niece of Houston’s mother Cissy Houston. Jones noted that Houston’s alleged molestation had a lasting effect on her life. “It made her question her sexual preference,” she notes in the doc. As for why Houston never told her mother: “I think she was ashamed,” says Jones. “If Cissy had known, she would have done something about it, because Cissy loves her children.”

Gary Houston, Whitney’s half-brother, also says he was sexually abused between the ages of 7 and 9 by a female family member in the film.

Whitney Houston died at the age of 48 on Feb. 11, 2012, having accidentally drowned in a bathtub following a heart attack brought on after years of substance abuse. Dee Dee Warwick died in 2008 at age 63.

Whitney, which was made with the cooperation of Houston’s estate, provides intimate insight into Houston’s personal life and struggles. Macdonald conducted around 70 interviews with everyone from Clive Davis to Houston’s Bodyguard costar Kevin Costner. It also touches on other aspects of the star’s troubled life, giving viewers a glimpse into her drug use as well as her tumultuous relationship with ex-husband Bobby Brown, who also appears in the documentary.

Macdonald alluded to the allegations when he spoke with EW last month prior to the debut of the first Whitney trailer, saying that the documentary would shed light into who Houston really was, and incidents that — for better or worse — affected her later in life. “There are many revelations in the film that I think I can’t really talk about right now, but which I think will, even to people who feel they know this story, will make a lot more sense of who she is and of these kind of things that we’re talking about,” he told EW.

While poring through hundreds of hours of private home footage for his film, Macdonald told Vanity Fair that he had suspicions that something horrible had happened in Houston’s life. “There was something very disturbed about her, because she was never comfortable in her own skin,” he told the publication. “She seemed kind of asexual in a strange way. She was a beautiful woman, but she was never particularly sexy. I’ve seen and done some filming with people who have suffered childhood sexual abuse, and there was just something about her manner that was reminiscent to me of that sort of shrinking.”

Macdonald foreshadowed to EW how viewers would see the connection to Houston’s family and how this influenced her sexual and romantic life. The documentary mentions Robyn Crawford — Houston’s longtime best friend and supposed romantic partner — and their alleged relationship. “She was the one person who loved her who really wanted to take part but didn’t,” Macdonald told to EW of Crawford. “I think it’s when you see the film, you’ll see she obviously played a big part in Whitney’s life, but it’s not the great key that unlocks who she is. I think it’s all about her family, really.”

EW has reached out to reps for Dionne Warwick and the filmmaker for further comment.

Whitney will be released in theaters on July 6.

Sarah Rodman provided additional reporting for this story.