I found this band through a great Spotify album, the Don't Mess with Texas: SXSW 2013 New Music Sampler (Spotify playlist below). It's perfect for me and a source of some good new stuff.
He's My Brother, She's My Sister is an L.A. band, originally formed by actual brother-sister duo Robert and Rachel Kolar, but now consists of five members. I think it particularly resonates because my brother Danny will sometimes say, "She's my sister" in this funny voice, and I love it. Their first full-length album came out back in October 2012, but they had an EP come out back in 2010. They're also currently touring.