Kris Jenner Shares Why She Cheated on Robert Kardashian

Kris Jenner is baring it all.

The Kardashians star—who was married to ex Robert Kardashian, Sr. for 12 years until their 1991 divorce—is opening up about why she was unfaithful to the late attorney. After daughter Khloe Kardashian asked her mom why she cheated in her past relationship during the latest episode of The Kardashians, Kris chalks up her decision to the mindset she had in her early 20s.

"I think being really young and dumb is something that plays into it," Kris—who also shares kids Kourtney Kardashian, Kim Kardashian, and Rob Kardashian with Robert—said during the Oct. …