Gia Kim and Sang Heon Lee | How Well Do You Know Your Co-Star | Marie Claire

Gia Kim and Sang Heon Lee | How Well Do You Know Your Co-Star | Marie Claire

Gia Kim and Sang Heon Lee took sibling rivalry to the next level in Marie Claire's How Well Do You Know Your Co-Star?

The real-life brother/sister pair and 'XO, Kitty' castmates talked secret tattoos, growing up together, and first jobs.

So let's see how well Gia Kim and Sang Heon Lee know each other