Sarah Silverman is airing a dark family secret.

On Sunday, Rolling Stone published a profile about the comedian in which she drops a bombshell about her brother Jeffrey’s death as an infant. Jeffrey, who was born five years before the “Saturday Night Live” alum, died at 3 months old in their grandparents’ care while their parents were away on a cruise.

“The story was that something happened with the crib, and Jeffrey’s little body slid and he got suffocated,” Silverman told the magazine.

Silverman said she never had any reason to doubt this story. That is, except for one confusing childhood incident involving her grandmother.

According to Silverman, when she was 5, her grandmother drove her and her three older sisters to breakfast. When her grandmother asked them to buckle their seat belts, Silverman decided to crack a joke.