Kourtney and Scott's first child, a son named Mason, was born on Dec. 14, 2009. Not only is he Kourtney's oldest, but he's also the first Kardashian grandchild.
On his 10th birthday, Kourtney and Scott both shared photos of their son with sweet captions. "Happiest tenth birthday to the boy who changed my heart forever. No one is cooler or sweeter than you," Kourtney wrote. Scott added: "It's just me and my best friend. 10 years of the best love ever."