In a sneak peek at Sunday’s episode of Keeping Up with the Kardashians, Kim Kardashian West, 37, and Khloé Kardashian, 33, sit down to watch a tribute video Scott Disick, 34, made for Jenner, 62.
“I’m really excited for my kids to see my legacy video,” says Jenner. “Because they’ll have that forever — and who knows, maybe they learned a thing or two about their mom that they didn’t know before.”
The footage shows Kourtney Kardashian‘s ex-interviewing Jenner, who reveals that her relationship with their late father — her first husband Robert Kardashian — started as a fling when she was dating somebody else.
“Back in the spring of 1973, I was 17 years old,” she says. “I actually had a boyfriend who was always out of town. His name was Cesar. So while he was living on the road, I met Robert Kardashian.”
Khloé wasted no time teasing her mom, calling her a “hussy” and quipping, “Oh my God, you’re such a whore! Now we know where we get it from.”
But Jenner’s story gets even juicier: One day when Robert was over, Cesar unexpectedly returned home.
“Well, it wasn’t pretty,” she admits. “Not proud of it. Actually, Cesar tried to grab his sweater. I think he ripped a hole in Robert’s sweater! I didn’t want to ever hurt anybody’s feelings.”
Jenner also reveals that she once had a bone tumor that would have caused her left leg to be amputated had it been cancerous.
“You did?” Khloé exclaims while watching the video. “I did not know that.”
“I cannot believe Scott made this legacy video,” Kim says.
“I think it’s so sweet,” says Khloé. “So much I think we think we know about mom — but we really don’t.
Keeping Up with the Kardashians airs Sundays (9 p.m. ET) on E!
This article originally appeared on PEOPLE.