Kim Kardashian could not have a better relationship with Caitlyn Jenner.
ET caught up with the 34-year-old reality superstar at the DailyMail.com's yacht party in Cannes, France on Wednesday, where she dished about spending time with Caitlyn on Father's Day. Caitlyn tweeted a picture of their family celebration on Monday, which featured Kim and husband Kanye West holding their daughter, North West, as well as Khloe Kardashian and Kendall Jenner.
"I told her she's a tomboy because she really likes off-roading and doing all the things that she did before," Kim told ET with obvious affection for the 65-year-old Olympian. "So we had a really good time. It was family, and we just had a chill day."
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Speaking of family, Kim confirmed that she's in touch with her younger brother, 28-year-old Rob Kardashian, despite the two making it no secret that they haven't always had the best relationship. However, Rob -- who has largely stayed out of the spotlight in the last year -- did recently make nice with Kim on Twitter, by sending her a voice note to help with her nausea.
"He sends me funny voice notes all day long," she said with a smile. "He always has, it's his thing. So he was sending me funny ones last night of him singing, which had nothing to do with the tweet helping me with my nausea. I think he was just trying to make me feel better singing."
Despite reports on his alleged 100-pound weight gain in the last year alone and rumors of depression, Kim said Rob is currently in good spirits.
"He has been, and that always makes me happy," she shared.
As for another one of her famous siblings, Kim commented on the constant comparisons between her and her youngest sister, 17-year-old Kylie Jenner.
"I love that," she laughed. "She is the best, you know? She's my little twin soul. She's such a free spirit, and I love that. She's the sweetest."
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Check out the video below to hear Kylie dish to ET about her 18th birthday plans!