Patrick Schwarzenegger's Sister Katherine on Miley Cyrus: 'I Approve of Whatever Makes My Brother Happy'

Miley Cyrus shows off her flat stomach while wearing a sports bra and hiking with friends on Thursday afternoon (April 16) in Los Angeles.

The 22-year-old entertainer’s boyfriend Patrick Schwarzenegger‘s sister Katherine recently opened up about their relationship.

PHOTOS: Check out the latest pics of Miley Cyrus

“I approve of whatever makes my brother happy,” Katherine told E! News. “He’s a 21-year-old college kid, how could he not be [happy].”

In case you missed it, Miley recently flashed her nipple during a racy photo shoot.

15+ pictures inside of Miley Cyrus getting her fitness on…