"Penelope & North are bff!" Kim told fans on the social networking Q&A site MobioINsider Sunday. "It's so cute how they all love each other so much!"
The Keeping Up With The Kardashians star's daughter is 6-months-old, while Penelope, the daughter of Kourtney Kardashian and Scott Disick, is 17-months-old. Kim added that North's older cousin Mason, 4, "bosses both of them around and is super protective."
Looking forward to celebrating Christmas Wednesday, Kim said, "They are all my family and we will all be together" at her mother's home in Calabasas, Calif.