Kendall Jenner Towers Over Sister Kourtney Kardashian in Instagram Pic

Looks like Kendall Jenner is the big sis now -- height-wise, that is!

The 19-year-old towered over her oldest sibling, Kourtney Kardashian, in this fun Instagram pic posted by sister Kim Kardashian.

Kim captioned the post, "Twins," and with their matching white button-down shirts and long dark locks, Kendall and Kourtney really do look alike!Kendall put on black heels while mom-of-three Kourtney, 36, went barefoot to exasperate their height difference. Without footwear, the Calvin Klein model is just shy of 5'11", while the eldest Kardashian kid tops out at 5 feet.