On Thursday night, Kelly Clarkson returned to where it all started: American Idol. Not only did the pop star serve as a guest judge, but she delivered an emotionally charged rendition of "Piece by Piece." Tearjerking performances from Clarkson are pretty common — remember how she and Josh Groban had everyone in tears during their Phantom of the Opera duet? — but this one really seemed to hit home. Clarkson, of course, blamed her hormonal pregnancy, which she announced at an LA concert back in August. We can't help but wonder, though, if coming home to American Idol had something to do with it, too. Watch the incredible performance above, then check out all of Clarkson's sweet family photos.