There's no denying the Kardashian/Jenner clan have had their fair share of ups and downs with feuds, friendships and family drama being played out on their show, The Kardashians.
While his close relationship with Khloe is well documented and Rob once made a confession that Kylie is his favorite sister, how does he feel about Kourtney?
Rob didn't attend Kourtney's wedding
When Kourtney tied the knot with Travis Barker in Italy in May 2022, Rob was nowhere to be seen. In fact, he didn't attend any of their three nuptials.
However, his absence wasn't down to any bad blood, but rather Rob's reluctance to step into the spotlight.
He lives a far more low-key lifestyle than his famous siblings and the presence of photographers at the event reportedly made him uncomfortable.
Their on-air argument
An iconic moment from Keeping Up with the Kardashians was when Kourtney expressed her anger at Rob's lack of effort when it comes to family life.
During a more challenging time in his life, when Rob was a regular on the club scene, Kourtney berated him for spending so long in bed recovering from his late nights.
"He's always hungover," she told Khloe. "All he does is go out and party his life away." She then added: "We are so family orientated but he lives at Khloe and Lamar's (Odom) house and just hangs out there all day.
"When she pulled Rob up on his behavior while he lay in his bed, he insisted he wasn't hungover and quipped: "At least I'm not belligerent like you and your friends."
But Kourtney was clearly unimpressed and later revealed: "I haven't spent quality time with Rob in months. Mason [her firstborn] is growing up so quickly and he's missing it."
Rob and Kourtney's age difference
The age gap of eight years may also be a factor in why Rob and Kourtney don't appear to be as close as he is to his other siblings.
Kourtney had her first child, Mason, 13, when she was in her early 30s while Rob was in a very different phase of his life.
Rob gave Kourtney her favorite gift
Proving that despite some tensions between them, he loves his sister, Rob gave Kourtney her "favorite birthday present" for her 41st birthday.
He presented her with their late father Robert Kardashian Sr.’s record collection. The heartwarming gift was revealed to fans on Instagram and it clearly touched Kourtney.
He's a great dad
Their connection is likely stronger now that Rob has a family of his own. He's been praised on numerous occasions by his siblings for being a "great dad" to his daughter, Dream.
Khloe shared the family's sentiments over Rob when she said: "He's literally the best dad I know and I'm so proud of him for that. I know that he's just feeling really good about himself and I'm happy for him. I have faith that soon he'll be back on the show."
Meanwhile Kourtney is now a mom to four children. She shares Mason, Penelope and Reign with her ex Scott Disick - who has remained friends with Rob - and she recently welcomed her son, Rocky, with her husband Travis.
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