Their daughters are BFFs, and so were they.
Kourtney Kardashian shared a seriously adorable sibling photo on Instagram just now, showing where little North and Penelope get their cuteness.
The mum-of-three posted a throwback snap of herself and her Kim as kids, wishing her 27m followers a "happy Halloween."
Dressed as a ballet dancer, the young Kourtney looks into the camera while her little sister, dressed as a tiny Wonder Woman, stares adoringly up at her.
Within minutes, Kim responded with an equally adorable snap from another family Halloween, this time including their mum Kris Jenner:
The stars' daughters, three-year-old Penelope and two-year-old North, prepped for October 31st just yesterday, donning Frozen-inspired Princess Elsa and Princess Anna costumes.
If there's one family who know how to do Halloween, it's the Kardashians… they've been in training from a VERY early age.