Kardashians Learn Biological Ages on Season Finale -- And Kim and Kris Are Pissed!

On Thursday's season finale of The Kardashians, she, sister Kim Kardashian, mom Kris Jenner and Scott Disick all had blood drawn for something called the Horvath test -- an exam designed to reveal one's biological age and determine how they're aging compared to their peers.

"It would be very ego-boosting if I was younger than my regular age," Kim said ahead of the test, while Disick assumed he'd discover he's "probably so much older" than his chronological age. "Kim's probably gonna be 15. I'm probably gonna be 70," he quipped -- while Khloe added, "There's no way I'm older than Scott. Scott used to party, I'll just say that."

Kim assumed she would be younger than her real age, believing all her health and beauty practices would be a "scam" if that wasn't the case. She also doubted her mom, Kris, would be "20 years younger, like she thinks."

Later in the hour, the group sat down together and learned the results from Dr. Matt Dawson, who appeared via video chat.

"Kris when I look at your results, the first thing is I measured biologic age. You are 6 years younger than your chronologic age," he told Jenner. While she seemed happy with the results, Kim said she could tell her mom was "pissed" in a confessional -- adding, "She thought she was gonna be, for sure, my age. Like, for sure. For sure."

For Kim, Dawson told her she should give herself "a pat on the back" for her results -- which came back as 34, a good 9.5 years younger than her actual age.

"It's incredible. That is a really amazing score. I think the most impressive thing, Kim, than just the age, is the pace of aging," he told her, saying she was aging 18% slower than most people her age.

Khloe then began to freak out as both Kim and Kris got positive results, fearing it wouldn't be the same for her. Turns out, she had nothing to worry about -- as the doctor called her a "world champion" ager, who was almost 12 years younger than her actual age.

"You're a child!" exclaimed Disick, as Khloe -- now 40 -- learned her results put her at 28.

"Never in a million years. If I had to bet money, I never would have bet on myself. Kim is livid, by the way. She is pissed," Khloe said in a confessional, before Kim confirmed she was, in fact, "pissed" over the situation. "I always want to be the highest achiever," Kim added.

The good news continued as the doctor told Khloe that she would be "number seven in the world" when it comes to "self-rejuvenation."

"The world needs to know that me, the fat one, is now better than the best one," Khloe gloated in a confessional. "[Kim] was always like, 'I'm the princess,' or whatever her tagline was. My tagline on [Keeping Up with the Kardashians] was I'm the fat, funny sister, if you look at the opening of the show. The fat funny sister is 12 years younger than her chronological age."

For Disick, his biological age was exactly the same as his calendar age, which the doctor explained usually means "in the past, you probably didn't focus on health as much as now." Scott admitted as much, saying there was "probably 10-15 years" where things got "pretty heavy" for him with drugs and alcohol. "15 years of beating myself down," he added.

In the end, Khloe said that while she "hated" the idea of this test in the beginning, she now felt it was "the best test I've ever taken in my f--king life" -- before thanking the "kids menu" and her mom's genetics for helping her out. Kim, meanwhile, admitted defeat .... and vowed to keep taking the test until she got a younger result.

The Kardashians Season 5 is available now on Hulu.