Thirty-five years ago in Louisville, Ky., one ambitious blastocyte performed an act of insurgent disunion inside one very unsuspecting womb. Nine months later, two masterly melodists came screaming into the world in perfect harmony – and they’ve been that way ever since.

“My sister and I made a pact that we would take any opportunity that came our way,” Chandra Watson said. Together, Chandra and her sister Leigh front the Los Angeles folk act The Watson Twins.

Fans of indie rock outlet Rilo Kiley may recognize them from lead singer Jenny Lewis’ solo album, “Rabbit Fur Coat,” of which the Twins sang backup vocals. “Rabbit Fur Coat” hit No. 6 on Billboard’s Top Independent Albums in 2006 when the album was released.

“It was a really great experience for my sister and I,” Chandra said, of touring with Jenny Lewis. “We learned a lot about being performers on the road.”

She describes performing backup for such a noteworthy artist as a pretty comfortable place to be.

“It took some of the pressure off,” Chandra said. “We were in front of everyone, we had to nail our part, but at the end of the day, Lewis was carrying the show.”

Since then, The Watson Twins have been busy ascending the totem pole of Americana music. Its first EP, “Southern Manners,” was released just as the two were going on the road with Lewis.

“Fire Songs,” the Twins’ first full-length album, followed in 2008. With a few “Fire Songs” tracks and the unreleased B-side, “Live at Fingerprints” is their most recent project.

“It’s a fun little acoustic EP that we made at a record store in Long Beach,” Chandra said.

The Twins are in the process of writing a new album.

“My sister and I mostly write separately,” she said. “We both have different things that are important to us. We spend a lot of time in our separate spaces forming these songs that we can find a connection to and feel passionate about. Then we bring them to the other person to discuss arrangements and work on the harmonies.”

According to Chandra, however, those melodious vocals don’t require too much work.

“I definitely think our (matching) genes have given us an advantage in having those instinctual harmonies,” Chandra said. “Leigh is the easiest person for me to sing with. She can start singing something I don’t even know and in 60 seconds I’m harmonizing with her. I instinctually know where she’s going to go with it.”

Chandra said classifying the twins’ music is not the simplest of tasks.

“It’s indie rock, it’s folk, it’s Americana … people who like all different styles of music can find something that they enjoy in it,” she said.