Kim Kardashian explains why she rarely smiles


Kim Kardashian Explains Why She Doesn't Smile Anymore
Kim Kardashian Explains Why She Doesn't Smile Anymore


Why so serious, Kim Kardashian?

The 34-year-old reality star is rarely seen showing off her pearly whites and Kim has a simple reason why she's often never smiling or laughing: wrinkles. Yup, wrinkles.

WATCH: Kim Kardashian in 1994 Home Video: 'When I'm Famous, Remember Me as This Beautiful Little Girl'

Kim made the revelation in a tweet Monday along with a candid black-and-white photo from her family's Christmas party of her and friend Shamari Maurice laughing it up and enjoying each other's company.

This content is not available due to your privacy preferences.
Update your settings here to see it.

While Kim -- ET's No. 1 headline-making celebrity of the year -- was all smiles for the holidays, the same can't be said for her adorable 1-year-old daughterNorth West when she met Santa for the first time.

NEWS: Kim Kardashian Explains Why She Cropped North West Out of Photo

"North West is still warming up to Santa," Kim wrote in the caption on the Instagram pic showing North not too thrilled about Santa's presence.

This content is not available due to your privacy preferences.
Update your settings here to see it.

The past 12 months have been busy for Kim, from her wedding to Kanye West to landing on the cover of Vogue to "breaking the Internet" with herPaper Magazine cover. Find out why 2014 may have been her biggest year so far!

Why 2014 Was the 'Kraziest' Year Yet to Keep Up With Kim Kardashian
Why 2014 Was the 'Kraziest' Year Yet to Keep Up With Kim Kardashian


More from ET
Nick Cannon slams rumors: 'I will never say anything negative about Mariah Carey'
Sofia Vergara and Joe Manganiello engaged? Actress spotted wearing giant ring in Hawaii
Hollywood's hottest bikini bods!