Happy Birthday Kourtney Kardashian. The eldest Kardashian sister has just turned 36 but from this throwback photo sister Kim posted we don't think she has changed a bit. She looked stunning showing off her legs for her Vegas party at 1 Oak. 'The Keeping up with the Kardashians' star paired a wolford body suit with a pleated Balmain skirt for a sleek yet flirty look. She finished her outfit off with some laced Tom Ford heels.